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Problems reading modbus REAL from energymeters

Anders

Hi!

I´m trying to read values from several Schneider iEM3250 energy meters, all of them giving me the same problem.
Refer to the manual for modbus info: (https://www.se.com/ww/en/product/A9MEM3250/iem3250-energy-meter---ct---modbus/)

For example, on page 60 there's a list of registers for voltages, starting at 3020 and incrementing by 2.
The document says size:2 and type Float32. Each being 16bit value I suppose which then makes sense.

In citect I connect using the MODBUS1 protocol, and addressing them as Holding, function 4 in citect.
So the addresses are 43020, 43022, 43024 ... etc.

All the phase-phase voltages reads good, but only the first two phase-neutral reads good. The last one reports -nan in runtime. (address 43032).

When using a modbus poll program (AVreporter modbus communication tester) I find that the addresses I read from citect varies a lot in value, while the following address stays quite still.
I suppose when addressing REAL citect combines two bytes into a REAL value?

All the addresses that works has a following value of around 17500, but the non-working address has a value of 65470.
I don´t know, but starting to guess that citect expects a signed INT, but gets an unsigned INT a freaks out?

Anyone got an idea?

Regards
Anders

Parents

  • I can´t say whether it´s connected as Y or D, but it is for reading voltages here in sweden, and in this case standard 3-phase 400V phase-phase and 230V phase-neural.

    I do read normal phase-phase voltages, all three phases. Addresses 43020, 43022, 43024. Voltages all ~400Volts. 

    But I can only see normal values for phase L1-N and L2-N. Addresses 43028, 43030. Voltages all ~230Volts.

    Where I should read phase L3-N I only get -nan as result. Address 43032.

    So it can´t be a question on physical connection, as the values I do get are normal. But some says -nan. Not A Number.

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  • I can´t say whether it´s connected as Y or D, but it is for reading voltages here in sweden, and in this case standard 3-phase 400V phase-phase and 230V phase-neural.

    I do read normal phase-phase voltages, all three phases. Addresses 43020, 43022, 43024. Voltages all ~400Volts. 

    But I can only see normal values for phase L1-N and L2-N. Addresses 43028, 43030. Voltages all ~230Volts.

    Where I should read phase L3-N I only get -nan as result. Address 43032.

    So it can´t be a question on physical connection, as the values I do get are normal. But some says -nan. Not A Number.

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