Automation Direct H2-DM1E Modbus TCP Communications
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Hi everyone,
I am a complete newbie, so please bear with me. I am setting up a Mango SCADA system for my Automation Direct system here at the malthouse. In anticipation of getting Mango running I have been experimenting with getting data from the PLC with ModBus TCP polls. I have used two ModBus clients, Modbus Scanner and Simply Modbus TCP Client. I used a spreadsheet provided by Automation Direct to convert the PLC holding registers to ModBus addresses. But I only get zero values back from the PLC when polling those registers. I can look on the PLC programming software and see there are non-zero values in the PLC registers. Any clues to what I am doing wrong would be very helpful. Thanks. -
Issue solved by the helpful folks on the Automation Direct Technical forum. Apparently the AD PLCs have a security feature that won't allow clients to access "protected" memory registers, i.e. the V word holding registers. You can only access the "ModBus" registers, i.e. MI, MR, MHR etc.
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Thanks for the info and for updating this topic.