Problem
Logging historical data from specifically a slower PLC model may stop after a while. At least one of the following errors is displayed in the StrideLinx router's log file and when doing a Run test at the variables in the StrideLinx Cloud:
PLCTAG_ERR_WRITE (-37)
PLCTAG_ERR_READ (-28)
This issue has been encountered with an Omron NJ101-9020 using the Ethernet/IP protocol to log 300 variables.
Cause
The PLC is unable to process all data requests within its own time limit of 10 seconds, breaking the connection prematurely by sending a connection reset (RST) and resulting in the above communication error.
Solution
Any of the following solutions can be applied to resolve the issue:
- Increase the timeout in the PLC, if at all possible.
- Upgrade the PLC hardware or replace it by one with better hardware specifications.
- In the StrideLinx Cloud, create a second identical data source and split the variables across both data sources to reduce the amount of data requested in one connection.