PM5310 integration in DCS systemEmerson DeltaV - problem with FLOAT32 registers

[Anonymous user]

Hello everyone,

I have a customer who has PM5310 connected to DCS system Emerson Delta V via Modbus RS485. He wants to read basic data like current, voltage and power. He reads them from the bellow registers, but the values he sees in the software are very different from the ones on the display. I think the problem is with the Float32, because we tried to read the CT Primary and Secondary, which are INT16U and the data was correct. Here are the registers he would like to read:

1 - Currents 3000-3004 FLOAT32

2 - Voltages 3020-3024 FLOAT 32

3 - Power 3060, 3068, 3076 FLOAT32 

Any idea what could be the problem?

Thanks and Regards,

Mariya

[Robert_Lee · Accepted solution]

If the DCS system is unable to properly interpret FLOAT32 values, the PM5xxx devices have no other registers available which only support 16 bit registers for meter readings (certain settings are defined as 16 bit when resolution isn't required).  There are obvious reasons why the firmware developers pick FLOAT32 for readings where users want to both be able to see both register resolution AND have large display ranges (ex. GW down to milliWatts) which FLOAT32 registers provide.

My guess is that the DCS system is attempting to read the FLOAT32 registers as 16 bit Modbus ones and showing those values which would be incorrect.  The customer needs to see if the DCS system is capable of reading FLOAT32 values instead.

[Ramasamy_N · Accepted solution]

You can suggest to read 2 registers in UINT16 format and convert it to FLOAT32 as per IEEE-754 converter.