EM1000 meter communication

[JayangaDivya]

Hi,

I checked the EM1000HLCD meter through the mod scanner. then it works properly. but another third-party monitoring system did not show data. what is the error?

[Charles_Murison]

Hello @JayangaDivya ,

There is not enough information to begin to answer this question. Almost all modbus requests are going to have a starting register X and a number of registers Y after that. Devices may behave different if using different starting registers or reading a size greater than Z. To do a true comparison you would need to know what the exact request, starting register and size, the third-party monitoring system sent to the device and make Mod Scanner send the exact same request. 

You also did not include details such as where Mod scanner was located relative to the 3rd party. Running on the same machine, verses different machines on same network verses different networks.  

 I am not EM1000 expert so I cannot speak to specifics of the meter. I can only speak about the generic troubleshooting.

Regards,

Charles

[JayangaDivya]

Hi @Charles_Murison 

please find attached an image relative to this issues 

[Charles_Murison]

Hello @JayangaDivya ,

I cannot begin to pretend I can follow most of the screenshots. One thing that did stick out to me is Modscan used Swapped float while Niagara used float. Perhaps that is enough of a difference.

Regards,

Charles

[Muhoro-Wandia]

Hi @JayangaDivya, I am trying to find the Modbus Register addresses for this meter (EM1000H LCD), but to no avail. By any chance, would you have a list of the registers kindly. 

Thank you.

[Robert_Lee · Accepted solution]

Modscan (and various other Modbus based software) uses what is known as PDM (Power Data Model) addressing where documentation and the software UI list addresses that range from 1 to 65535.  When communicating with Modbus devices however, the actual Modbus data frame uses PDU addressing which is the PDM address minus 1.

So for example, you are attempting to read the Frequency register which according to the 1000H documentation is listed as FLOAT32 located at register 3110 (which is likely a PDM address).  This would require the actual data address being requested as 3109.  It may be that your software is addressing PDU addresses directly (and not using PDM).

You could try setting the address in your software to 3109 instead of 3110 to see if it gives the expected result which would match what ModScan is showing when using the PDM address.