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I need help, I want to monitoring a multi function meter over RS485

Alex26

Feb 23, 2023
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Hello, this is my first post here, I would need help with a way to monitoring RS485 data with a window's PC. I have a multi function meter MFM376 I would like to monitor voltage, current, power, etc. Over RS485, I try some software that I find in the internet but it's not working. The manufacturer offers a monitoring software but it's very expensive. So I looking for a alternative solution that would be cheaper or free, I hope someone can help me.

Thank you in advance
Greetings Alex
 

Harald Kapp

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It seems the MFM376 uses the MODBUS protocol. The necessary parameters are listed in the manual. Any MODBUS capable software should be able to control the meter. E.g. this free tool.
 

Alex26

Feb 23, 2023
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It seems the MFM376 uses the MODBUS protocol. The necessary parameters are listed in the manual. Any MODBUS capable software should be able to control the meter. E.g. this free tool.
Hallo, thanks I just try it but I don't really get a good result, the numbers don't really make sense to me perhaps I doing something wrong, I am not experienced with modbus protocol (I am experienced with power electronics)
 

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kellys_eye

Jun 25, 2010
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The datasheet does say the RS485 is only applied on the MFM376-c version. Is yours the one with the suffix 'c'? It also shows the need to set the data stream parameters on the MFM device (baud rate etc) - have you done that?
 

Alex26

Feb 23, 2023
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The datasheet does say the RS485 is only applied on the MFM376-c version. Is yours the one with the suffix 'c'? It also shows the need to set the data stream parameters on the MFM device (baud rate etc) - have you done that?
I have the MFM376-C-CE-ROHS, I was setting up the parameters, the software is reading data but it's like arbitrary (random numbers). The data from the configuration like current transformer, network type, is right. But the momentary values, like voltage, current, power, etc. are unreadable random numbers.
 

kellys_eye

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You've only set the software to read the first 20 registers. Seems like there are an awful lot more than that 'in there'. Can you read them all i.e. increase the 20 to '999'......?
 

Alex26

Feb 23, 2023
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You've only set the software to read the first 20 registers. Seems like there are an awful lot more than that 'in there'. Can you read them all i.e. increase the 20 to '999'......?
I was try the maximum is 125, it's the same result.
 

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kellys_eye

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Have you tried changing a measured value and seeing if there is a corresponding change in the value(s) of any register(s)?
 

Alex26

Feb 23, 2023
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Have you tried changing a measured value and seeing if there is a corresponding change in the value(s) of any register(s)?
Yes, I was try and there is a change in the values, but as I said the numbers don't really make sense to me.
 

kellys_eye

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Do the changes affect only one register or more than one? How do the numbers correspond? i.e. if you double the value measured does the register value also double?
 

Alex26

Feb 23, 2023
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Do the changes affect only one register or more than one? How do the numbers correspond? i.e. if you double the value measured does the register value also double?
More then one change but for example 50v show similar to 230v, but they go to 0 if no voltage is applied, similar with the current
 

Harald Kapp

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The data framing needs to match between transmitter and receiver: Baud rate, number of start and stop bits, parity
 

Alex26

Feb 23, 2023
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I was checking all of the settings they are the same on both sides. I try different situations: 1. photo no voltage, 2. photo mains voltage, 3. photo 1 kW load
As you can see it's changing but the numbers don't make sense to me.
 

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