Westermo RM-115S - Manual (Page 26)

115S Serial I/O Module User Manual
Page 26 June 2011
4.2.2 Modbus Output Timeout on Comms fail
The module when being used as a Modbus Slave device has an output reset on comms
fail feature.
This means the outputs are turned off after a configured timeout if the module doesn’t
receive any Modbus polls to itself.
Note: The Modbus Output Timeout feature is available in Firmware version 2.02
and above.
To set the Modbus Output reset time use the configuration software (V1.09 and above)
and under the “Comms” tab you will see a “Modbus Output Timeout”. Select the
appropriate time and then press the “Set Comms” button and then resetting the module.
See Figure 4-2 above
Note that you will need to change the connection settings on the “Connect” page, and re-
connect to the 115S.
Maximum Output timeout is 34 minute 57 seconds.
Selecting 00:00 minutes and seconds will disable the outputs resetting.
Be aware the “Modbus Output Timeout” must be greater than the Modbus Master Poll
time or you will see the outputs reset before the next poll. Generally it is good practice to
configure the reset time to two or three times the Modbus poll time so as to ensure
accurate comms fail indication.
The “Modbus Output Timeout” can also be configured by the Modbus Master by writing
into register 204 in units of 32 msec.
E.g. A0 hex would be 5.12 seconds, 3A9 hex would be 30 seconds, and 249F
would be 5 minutes.
The module then needs to be reset for the settings to take effect.
Also the module must be operating in MODBUS mode, otherwise the reset outputs
feature is disabled, so the modules address must be set to something other than “00”.
If using the modules in ELPRO E-Series mode the Outputs also have a reset feature that
can be configured within the E-Series Configuration Utility.