Overrun Error

What does 1508.4 mean?

This status bit, when active (1), indicates that the Serial Communication Unit's (SCU) receive buffer overflowed because incoming data was received faster than the SCU could process it. This typically points to a mismatch in transmission speed or a processing bottleneck, leading to loss of received data.

• The baud rate set on the transmitting device (Destination Device) is higher than the baud rate configured on the SCU.
• The SCU or PLC CPU is experiencing high load, delaying the processing of incoming serial data from the buffer.
• A continuous stream of data is being sent to the SCU without sufficient gaps, overwhelming its receive buffer capacity.

Click steps to track your progress.

1. 1

   Verify that the baud rate setting on the SCU and the Destination Device are identical (e.g., 9600 bps or 19200 bps).

2. 2

   Check the PLC's CPU usage and scan time. Optimize program logic or reduce the frequency of communication requests if CPU load is high.

3. 3

   If possible, configure the transmitting Destination Device to send data at a slightly lower rate or with longer delays between frames.

4. 4

   Ensure the SCU's internal settings for receive buffer handling are optimal, if configurable through system parameters.