Understand lot behavior for negative balances
- Last UpdatedMar 25, 2025
- 3 minute read
AVEVA™ Production Management treats negative balances slightly differently for equipment with different lot behavior types.
Selective equipment
If the source equipment is selective, then when the selected lot does not have enough material to fulfill a movement request, the balance of the lot becomes negative, see Selective lot behavior. The negative balance is repaid only when material is moved specifically into the negative lot.
Queue-based equipment
If the source equipment is queue-based (LIFO, FIFO), AVEVA™ Production Management takes material from the lots in queue order, see LIFO lot behavior and FIFO lot behavior. When all lots reach a 0 (zero) balance, and there is not enough material to fulfill a movement request, AVEVA™ Production Management creates a debt lot with a negative balance. When a material movement goes into the equipment, the debt lot is repaid first.
When AVEVA™ Production Management is required to create a debt lot, if the movement has a source material class, but no specified material, AVEVA™ Production Management does not know which material to use for the debt lot. In this case, AVEVA™ Production Management uses the unknown material for the source material class to create the debt lot. The unknown material is defined in the material class.
If the movement has a destination material class, but no specified material, AVEVA™ Production Management uses the unknown material for the destination material class to create a credit lot. The difference between a credit lot and a normal lot is that the credit lot is of unknown material. A credit lot has a positive balance.
Weighted average equipment
If the source equipment is weighted average, then material is taken from each lot in weighted amounts, see Weighted average lot behavior. If there is not enough material across the lots to fulfill a movement request, then a debt lot is created.
When AVEVA™ Production Management is required to create a debt lot, if the movement has a source material class, but no specified material, AVEVA™ Production Management does not know which material to use for the debt lot. In this case, AVEVA™ Production Management uses the unknown material for the source material class to create the debt lot. The unknown material is defined in the material class.
If the movement has a destination material class, but no specified material, AVEVA™ Production Management uses the unknown material for the destination material class to create a credit lot. The difference between a credit lot and a normal lot is that the credit lot is of unknown material. A credit lot has a positive balance.
