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PLC_007_BOND

QJ71MT91 communication with Ignition Scada

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Hello all, I am trying to communicate with my Ignition SCada which runs on Linux machine. I want read and write PLC data registers from Ignition scada. I have used manual for QJ71MT91 by mitsubishi and configured as per instructions. I am accessing D13000 to D15100 and D15100 to d25000 data registers . When i connect PLC to linux machine the QJ71MT91 gives me COmm Err. LED gets ON. I dont know why is this happening since I have done configuration as per manual Please help Thanks Ashish

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Are you certain the PC is sending an appropriate request to the CPU? Have you tried to check the error code in the MT91 module? See what error it is detecting, the LED simply means it's an error, doesn't say what kind of error. Without more details, there's no way to troubleshoot.

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In addition to Crossbow's answer note that the ERR LED on the MT91 is persistant after an error is detected, which means it will not automatically turn off when the error is gone (e.g. if an initial request goes bad the LED will not go off by itself when the error is gone).

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the error code is 7383H . Yeah I am can view PLC tags in the OPC browser on Linux PC.

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Seems like you haven't completely configured your module, or you are asking for data that is not present... Look at the manual (see attached picture)

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I have checked module setting and as I want to use this module as slave only i need to define on Modbus® Device Assignment parameter. I am reading D13000 to D15100 and D15100 to D32000 registers. I have enabled file setting in PLC Parameter menu PLC File. Edited by PLC_007_BOND

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How many data are you trying to read at once? Is the error only in the initial processing or is it persistent (can you turn off the LED and see if it comes on again)? How does your client look like (do you have any config from it)? After some time, can you read all the devices or are som missing (and if, which are missing)? Did you check if your start address in both the server and client are 0 or 1 based? I would guess you are trying to read something that doesn't exist. Maybe you are reading 1 point below or 1 point above what is allowed in the PLC? Did you try to read only 1 device to see if that works fine? Start with the easiest; read only one device, then read one batch, then read several batches. You will notice when the error starts coming and you can pinpoint where the error is located

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ok thanx for reply i checked with Modbus Poll software. I am trying to read D13000 in this software and i checked the ping operation it is connected to PLC. But on Modbus Poll it is giving me error. Even I am only reading one word. In my software the address starts from 0.

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OK. Try doing the same test, only this time try to read D13001 - or even better read only D13005. That way we can ensure that the device you are trying to read from the client is the same in the server (and that the offset is correct)

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