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While communicating Twido PLC and Vijeo Citect on Modbus/TCP protocol, I am facing difficulty in getting data in SCADA. How to solve this problem.


First of all make sure that you have properly configure the Vijeo Citect communication forms. Please take note that if you are trying to communication via Modbus TCP then you must make sure that you will have to put the Address field of IO device form as 1. 

Secondly Modnet Driver of Vijeo Citect request the block of 250 bits in one request. Which means if you have created one variable of address %M0 in Vijeo Citect then it will request %M0 to next 250 bits. But in Twido the allocated Memory address is set to maximum used variable in Twido application. So if the requested memory address by the Vijeo Citect block is not available in Twido then the block will be rejected by Citect. To tackle this problem we have two option either request only those variable which are used in Twido application or Configure all the Memory address in PLC whether it is used or not.  To request for individual address put a prefix G in the memory address of Modbus variable for example G40001 in Vijeo Citect variable tag address.
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