Modify the Modbus Interface to accept 32-bit Unsigned Ints from the PLC
provide a data type to accept a 4 byte unsigned integer from the PLC. At this point, it would be stored in a 64-bit float in PI DA.
Clint Ramsey
shared this idea
Thank you for your feedback. We do not plan to add native support for 32-bit Unsigned Integers to PI Interface for Modbus Ethernet PLC. Please check out the workaround provided in the comments below.
2 comments
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b.hobby
commented
This only works if you can read the 2 x 16bit registers separately, I have a device that disallows reads from the second word of the 32bit unsigned int, currently I can use a 703 read and hope I never see the sign bit tripped.
I'd prefer native support for 32 bit unsigned intergers as am about to roll out a heap of PV inverters which the majority of registers are 32UINT and as above they refuse to allow 2 16bit reads.
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Colan Dray
commented
I was just working with a customer to read uint32 tags from the Modbus interface. We were successful in using Clint's workaround from PISquare here: https://pisquare.osisoft.com/message/78622-re-pi-modbuse-4-byte-unsigned-integer-uint32#comment-78622
Briefly, the workaround involves reading the first 16-bits and last 16-bits as separate uint16 tags (modbus interface data type 11). Then using Performance Equations or Analytics to combine the values with the following formula: float64 = highPoint*65536 + lowPoint.
Hopefully this helps others. Native support would be great!