Problem in Modbus Communication in Freelance 2013 SP1
In one of our Terminal Automation Projects, we are using Moxa Gateway as Modbus TCP/IP to Serial Interface. The O/P of Moxa Gateway is connected to Freelane 900F third Port through a network switch. On the serial side we are communicating with DBBV Actuators(Auma - make). The process application is that we need to write commands through Modbus Protocol to Actuators and in return we will get the desired feedback from Actuator and accordingly our further logic will work.
We have observed that the modbus communication to Actuators is not working properly. So many times it has been observed that when We write the command Actuators doesn't respond or actaute. But when we disable and enable back the processing sequenc in the modbus block in commissioning mode, Actuators(Valve) starts responding to modbus commands.
This happens for read block also, if we operate the actuators locally at field , changed status didn't change automatically. when we disable and enable back the Modbus Read block, the status gets uodated.
Some times when we disable it and enable it back communication starts, sometime we need to reapeat this operation twice.
The frequency of writing the commonad is very less, but reading is continous.
Can anybody tell what may be the reaon behind this and what is the solution for this.
The connection done are explained in PPT
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