Which bit in a counter tag indicates that the accumulated count has met or exceeded the preset value?

The bit that indicates the accumulated count in a counter tag has met or exceeded the preset value is the DONE bit. When a counter is implemented in a PLC program, it typically monitors the number of events or pulses that occur. Once the count reaches or surpasses the predefined limit set by the preset value, the DONE bit is set to indicate that the counting operation has been completed successfully.

This DONE status is critical in control applications where subsequent actions or processes are contingent upon the completion of the counting process. For instance, in a manufacturing scenario, once a specific number of items has been counted, the DONE bit can trigger the next step in a conveyor system or initiate a notification signal.

Other bits such as OVERRUN or ENABLE serve different purposes within the counter's functionality; OVERRUN might indicate that the counter has exceeded its maximum range, while ENABLE controls whether the counter is actively counting or not. The RESET bit, on the other hand, is used to clear the accumulated count back to zero. None of these other bits indicate the condition of completion relative to the preset threshold like the DONE bit does.