WELCOME TO

THE INDUSTRIAL WIKI

RESEARCH CONTENT IN GREATER DETAIL
Talk Page

DISTRIBUTION CENTER OVERVIEW

Print
Email
Save
Social

These are a few outlines of how various conveyor processes in distribution centers function.

Menu

Rx Pick Module

Once the Rx pick module is started, level one personnel will pick the product, pack the product into totes, and place the totes on roller conveyors. Totes will travel to the wheel gate. If the wheel gate is open, totes will stop at the package-present-photo discharge end of the conveyor. The conveyor will start moving again if the gravity wheel gate is in the down position with the gate limit switch maintained and the conveyor running. If the gate is open for more than a minute, the conveyor will start after the alarm chime sounds with the appropriate delay time.

Totes will proceed to level two by belt incline conveyor and spiral belt curve conveyors. The totes continue around the roller curve conveyor and down the belt decline conveyors. At the discharge of the conveyor, totes will block the package-present-photo ramp and continue onto the level two pick line if the gravity wheel gate conveyor is in the down position with the gate limit switch maintained and the conveyor running. Conveyors will stop when the package-present-photo ramp is blocked, if the wheel gate is up, or the roller curve is not running. This will flash the level one green beacon slowly.

On level two, the operator will pick the product, pack the product in a tote, and place the tote on roller conveyors. From there, the totes will be conveyed over meter belts, which have two belts mechanically linked to provide a gap between totes. The movement of the belt is controlled by an air-operated clutch/brake assembly. As totes approach the discharge end of the belt meter, they pass under an overhead scanner. The scanner will read the barcode on top of the tote and serially transmit the barcode data to the PLC. In turn, the PLC will send the stats received from the scanner to SortView over the Ethernet network. At the discharge end of the meter belt is the package-present-photo. When this package-present-photo is blocked, an interlock from the strapper is examined by the PLC.

If the interlock indicates that the strapper is not ready to accept a tote, or if the belt is not running, the clutch solenoid is de-energized to apply the brake and stop the meter belt. At this time, the discharge zone control solenoid is de-energized to remove the drive from the discharge zone rollers of the roller conveyor and allow normal accumulation. If totes accumulate on the roller conveyor to block flow control photo for three seconds, it will stop. GSM will display the flow control condition. Normal product flow will continue from the roller conveyor when the photo has been clear for three seconds.

When the interlock indicates that the strapper can accept a tote, the clutch solenoid for the meter belt will be energized to discharge the tote into the strapper, and the discharge zone control solenoid is energized to provide drive to the discharge zone rollers of the roller conveyor.

The strapper will place a plastic band around the tote in preparation for shipping. Totes leave the strapper and cross the roller gravity gate onto the roller conveyor. The gravity wheel gate acts similar to other gravity gates, except that rather than stopping the upstream conveyor, the run enable interlock to the strapper is shut off. This does not allow the strapper to request another tote from the meter belt. The strapper run enable is also dropped out for a belt incline not in running condition.

Totes will travel up to level three by roller curve belt. Level three will consist of the accumulation conveyor. No picking operation is to take place on this level. On the conveyor, the totes will pass package-present-photo, which are the 100%, 75%, and 50% full photo eyes, respectively. At the discharge of the conveyor, totes will travel around a curve, up the incline belt, around another curve belt, and over the belt transportation conveyor to the accumulation conveyor. On this conveyor, totes will pass the 25% FulPhoto system. The accumulation conveyor unit will convey the totes to the meter belt for the shipping merge controlled from the control cabinet.

With normal accumulation on the conveyor, totes will eventually block 25% of the FulPhoto system. When this photo has been blocked for three seconds, a message will be sent to the shopping merge control cabinet that this pre-merge accumulation line is 25% full. The GSM will display the 25% full condition. The conveyor units will stop. Totes will continue to accumulate and block at a percentage for 3 seconds until there is a complete percent block and GSM reads a 100% block. The 25%, 50%, 75%, and 100% levels of fullness will be used by the shipping merge for the determination of merge pivot belt positioning. Normal product flow will continue when the photo system has been clear for three seconds.

Rx Pick Module Replenishment

Once the Rx pick module replenishment is started, operators will place cases of the product on one of the four lines in the staging area. At level one, operators will place cases onto the conveyor. Cases placed on the conveyor will flow over the ramp to block the package-present-photo system. If both sides of the gravity roller gate are in the down position with gate limit switches maintained the conveyor will stop when the package-present-photo is blocked, and if either side of it is up or if the conveyor is not running or full, green beacons will slowly flash. When cases have accumulated on the conveyor to block the flow control photo system for three seconds, conveyors will be full. When the flow control photo system is clear of product for three seconds, the conveyor will be available to accept more products. The GSM will display the flow control condition. Cases placed on the conveyor will flow over the ramp to block the package-present-photo system. If the gravity roller gate is in the down position with the gate limit switch maintained, and if the conveyor is running, then cases will continue over the gravity roller and onto the roller curve belt. Conveyors will stop when this package-present-photo is blocked if the gate is up or if the conveyor is not running. This will flash a green beacon slowly. Cases will continue from the conveyor and flow over the ramp to block the package-present-photo system. If both sides of the gravity roller gates are in the down position with gate limit switches maintained, and if the conveyor is running and not full, then cases will continue over the gravity roller gate and onto the roller accumulation conveyor. Conveyors will stop when the package-present-photo is blocked if either side of the gate is up or if the conveyor is not running or full. This, again, will flash green beacons slowly. When cases have accumulated on the conveyor to block flow control for three seconds, the conveyor will be full. When the flow control photo system is clear of product for three seconds, the conveyor will be available to accept more products. The GSM will display the flow control condition. At level two, operators will place cases onto the conveyors. Cases placed on the conveyor will flow over the ramp to block the package-present-photo system. If both sides of the gravity roller gate are in the down position with gate limit switches maintained, and if the conveyor is running and not full, then cases will continue over the roller gates and onto roller accumulation conveyor. When cases have accumulated on the conveyor to block flow of the control photo system for three seconds, the conveyor will be full. When the flow control photo is clear of product for three seconds, the conveyor will be available to accept more products.

AS/RS Pick Module

Personnel will place cases on conveyors on all levels of the pick module. Cases picked on level one will be placed on the conveyor belt. Cases placed on the belt will proceed to the package-present-photo system. The belt will continue to run if the gravity roller gate is in the down position with the gate limit switch maintained and running. The conveyor belt will stop when the package-present-photo is blocked if the gravity roller gate is up and the belt is not running. This will flash a green beacon slowly.

Cases will travel across the gravity roller gate and onto the belt. Cases will proceed to the package-present-photo system. The belt will continue to run as long as the gravity roller gate is in the down position with the gate limit switch maintained and the belt running. The conveyor will stop when the package-present-photo is blocked, if the gravity roller gate is up, or the belt is not running. This will also flash a green beacon slowly.

Cases will proceed to level two by belt incline and spiral belt curves. On the belt, cases will block the package-present-photo and continue onto the level two pick line. This is only true if the gravity roller gate is in the down position with the gate limit switch maintained and the belt running. Conveyors will stop when the package-present-photo is blocked, if the gravity roller gate is up, or the belt is not running. This, too, will flash a green beacon slowly.

Level two personnel will pick cases and place them on pick belt conveyors. Cases placed on the belt will proceed to the package-present-photo system. The belt will continue to run if the gravity roller gate is in the down position with the gate limit switch maintained and the belt running. The conveyor will stop when the package-present-photo is blocked, if the gravity roller gate is up, or the belt is not running. This, again, will flash a green beacon slowly. The conveyor is full when 100% of the FulPhoto system is blocked for a continuous 2.5 seconds. When the package-present-photo system is clear for three seconds, the conveyor is available to accept additional cases. The cases are transported out of the module on the conveyor. Cases flowing from the discharge end of the conveyor are under the control of the control cabinet.

Split-Case Module 2

With the split-case system starts, operators will put the product into totes that will manually be placed on pick belt conveyors on all levels of the split-case module. Totes on level one will be placed on conveyors. These totes will proceed to the package-present-photo system, and the conveyor will continue to run if the gravity wheel gate is in the down position with the gate limit switch maintained and the belt running.

Conveyors will stop when the package-present-photo is blocked, if the gravity roller gate is up, or the belt is not running. This will flash the level one green beacon slowly.

Level two personnel will place totes on the pick conveyor. Totes on the conveyor will proceed onto the accumulation conveyor. If totes accumulate on the conveyor, they will eventually block the flow control photo system. When this photo has been blocked for 3 seconds, the conveyor will stop, and the green beacon will flash slowly.

Level two personnel will place totes on pick conveyors. Totes conveying on the conveyor will proceed onto the accumulation conveyor. If totes accumulate on the conveyor, they will eventually block the flow control photo system. When this photo has been blocked for 3 seconds, the conveyor will stop, and then the green beacon will flash slowly. The conveyor will restart, and the beacon will stop flashing when the flow control photo system has been clear for 3 seconds.

From the conveyor, totes will convey over the belt. The conveyor has two belts mechanically linked to provide a gap between cartons. The movement of the belt is controlled by an air-operated clutch/brake assembly. As totes approach the discharge end of the belt, they pass under an overhead scanner. The scanner will read the barcode on top of the tote and serially transmit the barcode data to the PLC. In turn, the PLC will send the data received from the scanner to SortView over the Ethernet network. At the discharge end of the belt is the package-present-photo system. When this package-present-photo is blocked, an interlock from the strapper is examined by the PLC in the control cabinet.

If the interlock indicates that the strapper is not ready to accept a tote, or if the belt is not running, the clutch solenoid system is de-energized to apply the brake and stop the meter belt. At this time, the discharge zone control solenoid is de-energized to remove the drive from the discharge zone rollers of the conveyor and allow normal accumulation. If totes accumulate on the conveyor to block the flow control photo system for three seconds, the conveyor will stop. The GSM will display the flow control condition. Normal product flow will continue from the conveyor when the control photo system has been clear for three seconds.

When the interlock indicates that the strapper can accept a tote, the clutch solenoid for the belt will be energized to discharge the tote into the strapper, and the discharge zone control solenoid will be energized to provide drive to the discharge zone rollers of the conveyor. The strapper will place a plastic band around the tote in preparation for shipping. Totes leave the strapper and cross roller gravity gates onto the belt. The cross roller gravity gate acts similar to other gravity gates, except that rather than stopping upstream from the conveyor and the run enable interlocks to the strapper are shut off. This does not allow the strapper to request another tote from the belt. The strapper run enable is also dropped out of a belt that is not in running condition. The totes travel to the accumulation conveyor and, upon leaving, are no longer under the control of the cabinet control. Totes will accumulate on the conveyors and process in the same way the other components function. The product will release from the belts and will be inhibited when the package-present-photo system is blocked. A message will be sent to the shipping merge control cabinet that this pre-merge accumulation line is 100% full. The GSM will display the full condition. The percentage of fullness will be used by the shipping merge to determine the merge pivot belt positioning. The conveyors, belts, and normal product flow will continue when the photo system has been clear for three seconds.

Tub-Pick Module Systems

Operators will put the products into totes. These totes and any empty tubs from the racks will be manually placed on roller accumulation conveyors on all levels of the tub-pick module. Totes and empty tubs will be placed on the level one conveyor and moved to a meter belt. These totes/tubs will proceed to the package-present-photo and will be blocked if the vertical lift is not ready to accept the product. Totes proceed to level two by vertical lift and are discharged onto an area where the personnel will place totes and empty tubs on a roller accumulation conveyor, then move to a meter belt that has two belts mechanically linked to provide a gap between cartons. The movement of the belt is controlled by an air-operated clutch/brake assembly. As the totes/tubs approach the discharge end of the meter belt, they pass an overhead and side-mounted scanning system. The overhead scanner will read the barcode label on top of the tote, and the side-mounted scanner will read the barcode label on the side of the tub. The scanning system will serially transmit the barcode data to the PLC. In turn, the PLC will send the data received from the scanner to SortView over the Ethernet network. Package-present-photo is at the discharge end. If the interlock indicates that the strapper is not ready to accept a tote/tub, the clutch solenoid is de-energized to apply the brake and stop the meter belt. At this time, the discharge zone control solenoid is de-energized to remove the drive from the discharge zone rollers and allow normal accumulation. If totes/tubs accumulate on the conveyor to block the flow control photo for three seconds, the clutch solenoid will be de-energized to stop, and a green beacon will flash slowly. The clutch solenoid will be energized to start, and a beacon will illuminate steadily when the flow control photo has been cleared for three seconds. A strapper will place a plastic band around the tote in preparation for shipping. Tubs will not receive a band. Totes/tubs leave the strapper and cross the roller gate and onto the personnel gate conveyor. When the gate is opened, the run enable interlock to the strapper is shut off. This does not allow the strapper to request another tote from the personnel gate conveyor. The strapper run enable is also dropped out for a conveyor not running. Totes/tubs will be tracked up a belt incline and are tracked to a pusher diverter. If the tracked item is a tote, the pusher divert is not actuated, and the tote continues on. If the tracked item is a tub, the solenoid is energized to cycle the ram on the pusher diverter, and the tub is pushed onto the conveyor. Totes that continue will be conveyed to the accumulation conveyor. Tubs that are diverted will be conveyed down a decline belt to the meter belt. The meter belt will stop when the package-present-photo is blocked. The GSM will display the flow control condition. The stopped units will restart, and normal product flow will continue when the conveyor has been cleared for two seconds. Tubs that are diverted onto the conveyor will be conveyed down the decline belt, over the accumulation conveyor, and to the meter belt. From there, tubs will convey around a curve, down a chute, and over a ramp, where tubs will accumulate behind a fixed stop at the discharge end for use by operators.

Tub Module Outbound to Merge

Once the cabinet has been started, the totes will arrive from the controlled accumulation conveyor to the meter belts. These meter belts have two belts mechanically linked to provide a gap between cartons. Totes from level one and two convey over to the package-present-photo. Totes from level three and level four convey over to the package-present-photo, but when the package-present-photo is blocked, totes are not to be released from the conveyor and it is stopped. This will de-energize the discharge zone control solenoid to remove the drive from the last accumulation zone and allow normal accumulation. From the meter belts, totes are merged together on the conveyor. The release of the product to the merge will operate on a shared-time basis, where the totes from the conveyor are released to a ramp for 10 seconds, and the totes from the conveyor are released. If one meter belt runs out of product to release, then the other side will have exclusive use of the merge until the product is again present on the opposite meter belt. Totes will continue from the merge unit to roller accumulation. With normal accumulation on the conveyor, the products will eventually block the flow control photo. When this photo has been blocked for two seconds, the conveyor will be stopped, the discharge zone control solenoid will be de-energized to remove the drive from the last accumulation zone and allow normal accumulation, and the GSM will display the flow control condition. Normal tote flow will continue when the conveyor has been cleared for two seconds. With normal accumulation, the product will eventually block 25% of the photo. Once this photo has been blocked for two seconds, a message will be sent to the shipping merge control cabinet that this premerge accumulation line is 25% full. The GSM will display the 25% full condition. When the GSM displays the full condition, normal case flow will continue, and the green START beacon will illuminate steadily when the conveyor has been cleared for two seconds. The percentage levels of fullness will be used by the shipping merge for the determination of merge pivot belt positioning.

Tub Module Inbound

Personnel will fill tubs with product at both levels of the tub module. At level one, products will be picked from pallets and placed in tubs. The tubs will be placed on conveyors. They will then proceed, and at the discharge of the conveyor, the tub will block the package-present-photo. If the vertical lift is ready to accept the tub, it will continue over and into the vertical lift conveyor. If it is not ready to accept the tub, the tub will be stopped at the package-present-photo until the vertical lift is ready for the tub. When the conveyor at the package-present-photo stops, the discharge zone control solenoid is de-energized to remove the drive from the discharge zone rollers to allow normal accumulation. The vertical lift will deliver the tub to level two and discharge the tub onto the conveyor, where tubs from level one are merged with tubs from level two conveyors. From there, the tub will convey over the roller accumulation conveyor to the meter belt. As the tub conveys, the product will be checked by overheight photos to make sure it is not protruding over the top of the tub. If the product is too high, the photo will be blocked, the meter belt will stop, and beacons will be illuminated. Whenever the meter belt stops, the discharge zone control solenoid is de-energized to remove the drive from the discharge zone rollers to allow normal accumulation. If tubs accumulate on the belt to block the flow control photo for three seconds, then the vertical lift will be stopped. Normal operation will continue after the photo has been cleared for three seconds. If no overheight error is detected, the tub will convey to the package-present-photo at the discharge of the meter belt. The tub will be stopped at this photo if the conveyor has a tub anywhere along its length. When the belt stops, the discharge zone control solenoid is de-energized to remove the drive from the discharge zone rollers to allow normal accumulation. As the tub approaches the end stop at the discharge, a barcode scanner will read the label on the side of the tub and transmit the data read to the PLC. The PLC will, in turn, transmit the data received from the barcode scanner to the material handling computer (MHC). The MHC will transmit the tub data to the AKL that will come to the discharge end of the conveyor, pick the tub, and store it in the appropriate rack position. When the AKL has removed the tub from the conveyor, the next tub will be discharged. At level two, the product will be picked from pallets or picked from cases delivered to the conveyor by the replenishment sorter. The product will be placed in tubs. When the picking operation to the tubs is complete, the tubs will be placed on level two conveyors and will proceed over the brake belt. At the discharge, the tub will block the package-present-photo. If a tub is already enroute to level two from level one, then the conveyor will stop when the belt is blocked. When a tub is not en route to level two from level one, the belt will discharge the tub onto the conveyor. From this point, the conveyor operation will be identical to what is described previously.

'''NOTE:''' The operation of the opposite side pick conveyors will be identical to what is described above.

Lower Level Fire Door Cabinet

The control cabinet controls the conveyors passing through the lower row of firewall openings in the wall that divides the AS/RS highrise area from the remainder of the building. The conveyors controlled include the units immediately upstream of the firewall, the unit within the firewall, and the unit immediately downstream of the firewall (three units total) for each line affected.

If a fire signal is detected from the building fire system, all conveyors feeding and taking product away from the fire wall area will stop except for those controlled by the control cabinet. The conveyors controlled will initiate a fire door clearing sequence. All lines are similar, so only one will be described. Upon a fire signal, the brake belt will run until the package-present-photo detects a gap, at which time it will stop. The belts and conveyors will continue to run for an additional 10 seconds after the door-clear-photo is cleared and will also stop. If no gap is found at photos, the three conveyor units through the door will continue to run for a maximum of 30 seconds and then stop. When the conveyor system has determined that the door is clear, a dry contact will close, signaling the building fire system to initiate closing of the fire door. Limit switches are mounted near the top of each fire door frame and held in the closed state by the door. When a door begins to close, the limit switch actuator will fall off the door and open the circuit to the PLC input. If one of the limit switches detects that a door is closing, the control cabinet will initiate a fire door clearing sequence exactly as if a fire alarm was received. During normal operation under a flow control or stop condition, a clearing sequence is initiated through the fire doors to ensure that the door is cleared of product while the conveyor is stopped. If the downstream accumulation unit senses a 100% full condition or is stopped, the belt will run until the package-present-photo conveyor detects a gap, at which time it will stop, and the belt will continue to run for an additional 10 seconds after the door-clear-photo is cleared and then will also stop.

ASRS Pick, Level three Outbound

Once the cabinet has been started, the cartons will arrive from the cabinet controlled accumulation conveyor to the meter belt. It has two belts mechanically linked to provide a gap between cartons. On the discharge end is a package-present-photo. When the package-present-photo is blocked, the gap since the previous carton left the meter belt is determined. If the gap between the cartons is not large enough to allow proper diverting, the meter belt’s clutch solenoid will be de-energized to stop the meter belt. At this time, the discharge zone control solenoid is de-energized to remove the drive from the discharge zone rollers and allow normal accumulation. With the proper gap established, the clutch solenoid will be energized to convey the carton the belt onto the sorter. The discharge zone control solenoid is energized to provide drive to the discharge zone rollers.

As the case conveys, Update Photo 1 is blocked, and tracking of the carton begins. As the carton continues on the belt, the scanner’s READ photo is blocked. The scanner will scan the carton for a valid barcode and transmit the barcode information read to the PLC. If no valid barcode is read, the scanner will transmit zeros. When the carton blocks Update Photo 2 on the barcode, information received by the PLC is transmitted to the SortVIEW computer. The PLC will examine the case and, based upon information in the code, decide if the package will divert to Replenishment or continue to Shipping. The case is tracked to the pop-up wheel diverter. If the carton is destined for Replenishment, the divert solenoid is energized to raise the divert wheels above the conveying surface and guide the carton onto the takeaway conveyor. If the carton is destined for shipping, the divert wheels are left lowered, and the carton continues onto roller curve conveyor. Cartons diverted onto the belt will flow over conveyors to accumulation conveyors. Cases on belts will pass 100%, 75%, and 50% full photos to the fire door units controlled by the cabinet control. From the fire door units, the carton will continue on the conveyor to the replenishment merge. With normal accumulation of the belt, the product will eventually block 25% of the full photo. When this photo has been has been clocked for two seconds, an interlock signal will be sent to stop the fire door conveyors in the control cabinet, the GSM will display 25% full condition, and the product will accumulate on the conveyor. Normal case flow will continue when the belt has been clear for 2 seconds.

When cases accumulate to block 100% of the full photo for two seconds, the conveyor will stop, and the release of the product from the conveyor will be inhibited when the package-present-photo is blocked. The GSM will display the full condition. Normal case flow will continue when the ramp has been clear for two seconds. Cartons not diverted will continue on, and at discharge, the packages will travel over the fire door units. From the fire door units, the carton will convey over the belt, and then the carton will pass the 75%, 50%, and 25% full photo eyes to the shipping merge controlled by the control cabinet. Product will continue to accumulate and block 75% of the full photo for two seconds. At this time, an interlock signal will be sent to stop the fire door conveyors on the control cabinet, a message will be sent to the shipping merge control cabinet that this pre-merge accumulation line is 75% full, the GSM will display the 75% full condition, and the product will accumulate on the conveyor. Normal case flow will continue when the belt has been clear for two seconds. When cases accumulate on the belt to block 100% of the full photo for two seconds, the conveyors will stop.

The release of the product from the conveyor will be inhibited when the package-present-photo is blocked. A message will be sent to the shipping merge control cabinet that this pre-merge accumulation line is 100% full. The GSM will display the full condition. The 25%, 50%, 75%, and 100% levels of fullness will be used by the shipping merge for the determination of merge pivot belt positioning.

Audit Line

Selected totes are diverted from the shipping sorter and flow over to the discharge end. Totes will accumulate on the conveyor to block the flow control photo ramp. When this photo has been blocked for two seconds, the belt will stop, and the discharge zone solenoid on the ramp will be de-energized to remove drive from the last accumulation zone. Totes will accumulate on the ramp. The stopped conveyors will restart without a warning device sounding and normal tote flow will continue when the ramp has been cleared for two seconds. Totes that accumulate on the ramp will eventually block the flow control photo. After two seconds of photo blockage, the conveyors will stop, and the discharge zone solenoid will be de-energized to remove drive from the last accumulation zone. Totes will accumulate on the ramp. The stopped conveyors will restart without a warning device sounding, and normal tote flow will continue when the conveyor has been clear for two seconds. Totes that accumulate on the conveyor will eventually block the flow control photo. After this photo has been blocked for 1.5 seconds, diverts from the shipping sorter to the conveyor will be inhibited. Diverting of totes will resume when flow control photo has been clear of two seconds.

Hospital Line

Totes and cartons that have labels that cannot be read by the scanner, or have more than one label read by the scanner, or have labels that are untranslatable, will be diverted from the shipping sorter to the conveyor. This product will continue over a ramp to a fixed stop at the discharge end. The product will accumulate on the conveyor to block the flow control photo. When this photo has been blocked for two seconds, the ramp will stop, and the discharge zone solenoid conveyor will be de-energized to remove drive from the last accumulation zone. Totes will accumulate on the conveyor. The stopped conveyors will restart without a warning device sounding, and normal product flow will continue when the conveyor has been clear for two seconds. Product that accumulates on the conveyor will eventually block the flow control pot. After this photo has been blocked for 1.5 seconds, diverts from the shipping sorter to a conveyor will be inhibited. Diverting of the product will resume when the flow control photo has been clear for two seconds.

Bypass Line

Totes and cartons that are on the shipping sorter, but belong on the replenishment sorter, will be diverted from the shipping sorter to the conveyor. This product will continue over various ramps to the replenishment merge controlled by the cabinet controller. The product may accumulate on the conveyor to block the flow control photo ramp. When this photo has been blocked for 1.5 seconds, the conveyors will stop, the discharge zone solenoid ramp on the conveyor will be de-energized to remove drive from the last accumulation zone, and the GSM will display the flow control condition. Product will accumulate on the conveyor. The stopped conveyors will restart without a warning device sounding, and normal product flow will continue when the conveyor has been cleared for two seconds. Products that accumulate on the ramp will eventually block 25% of the full photo conveyor. After two seconds of photo blockage, the conveyors will stop, the discharge zone solenoid will be de-energized to remove drive from the last accumulation zone, and the GSM will display the 25% full condition. The product will accumulate on the conveyor; the stopped conveyors will restart without a warning device sounding, and normal product flow will continue when the conveyor has been clear for two seconds. The stopped conveyors will restart without a warning device sounding, and normal product flow will continue when the conveyor has been clear for two seconds. Also located on the conveyor is 50% of the full photo ramps. When product has accumulated to block this photo for two seconds, a status indication will be sent to the GSM. Accumulation will occur up to 75%. Products will eventually block the flow control photo, and after this photo has been blocked for 1.5 seconds, diverts from the shipping sorter to the conveyor will be inhibited. Diverting of product will resume when the flow control photo ramp has been clear for two seconds. Product that accumulates on the conveyor will eventually block flow control photo ramps. After this photo has been blocked for 1.5 seconds, diverts from the shipping sorter to the conveyor will be inhibited. Diverting of product will resume when the flow control photo has been clear for two seconds.