Help reading a Natural Gas Totalizer on PME 8.2 - FCI ST80 64 bit double precision register

[eskobar]

Good evening, everyone.

I kindly ask for your help in this matter, I'm an energy engineer with limited knowledge on industrial communications.

I am installing natural gas meters on my facility and I am having trouble getting the correct value from the modbus registers of an FCI ST80 unit.

I have this information:

And this is the configuration I'm using on PME modbus device importer:

The real totalizer is around 6,173,125 normal cubic meters and the value is in trillions ...

Thanks for your help.

[Romain_Polette · Accepted solution]

Hello @eskobar , 

For standard Modbus, a register is codded on 16 bits:

• If your value is UINT16/INT16 => you need 1 Modbus register to store your value.
• If UINT32/INT32 => you need 2 Modbus registers.
• If FLOAT32 => you need 2 Modbus registers
• If UINT64/INT64 => you need 4 Modbus registers

Your document said that your device is using "Daniel" Modbus extension. In this case, a Modbus register is codded on 32 bits.

PME is not compatible with Daniel or Enron extension. 

Please try with the 4xxx registers listed in table 24 and keep in mind that your Less Significant and Most Significant bytes are inverted in your table.

Example: For your device, "Flow" is codded on 2x INT16 registers. Usually LS byte would be on 4100 and MS byte on 4101. But in your case, this is inverted. 

Try the following on PME DTE (I'm not sure for your Float 64 value...):

Regards, 

[eskobar]

For the record.

Thanks a lot, Romain. Your post helped me a lot to get the correct register.

Quite franlky, I didn't understood how the register in the document should be readed, the most significant and the less significant byte confused me, I thought they were separate register and values.

When you confirmed that Daniel / Enron were not supported on PME 8.2, I re-read the manual and understood that the correct register was:

4105 in F64 big endian. I tried it and corrected all the inverted registers and that worked.

Thank you very much.