What is the maximum number of TCP connections on an I/A Series R2 UNC running a Modbus TCP driver?

Issue

What is the maximum number of TCP connections on an I/A Series R2 UNC running a Modbus TCP driver?

Product Line

TAC I/A Series

Environment

I/A Series R2, UNC-410, UNC-520

Cause

What is the maximum number of TCP connections on an I/A Series R2 UNC running a Modbus TCP driver?

Resolution

The recommended maximum number of connections is 24.  The Modbus document specifies the following.

maximumConnections: Default is 1 (one). If multiple Master TCP devices need to simultaneously access the station as a Modbus slave, set this to that number.

Note Each Modbus TCP device and/or Modbus TCP gateway shadowed in the station uses a separate station processing thread for device communications. Only finite amount of processing threads are available. To ensure proper performance, these maximum limits of Modbus TCP devices or gateways are recommended in any station, by JACE (UNC) platform.

JACE-4 (UNC-410) and JACE-5 (UNC-510 and UNC-520): 24 maximum