Hello,
I am looking for insight on why analog input module data type changes between INT and WORD for different use cases. I understand underlying data is consistent but I would like to structure code to use explicit conversions.
750-469 with PFC200 KBUS - INT
750-469 with 750-362 Modbus coupler - WORD
750-455/040-000 with PFC200 XTR KBUS - WORD
Thanks,
mb.
The 750-469 with the PFC200 via the K-Bus is mapped as an INT because the temperature values can be both negative and positive.
The 750-469 used with the 750-362 operates over Modbus, which uses 16-bit registers. The coupler itself does not define how the data should be interpreted - it is up to the user to decide whether to treat the value as an unsigned word (0 to 65,535) or a signed integer (−32,768 to +32,767). For the 750-469, the data should be interpreted as a signed integer, since that is how the module encodes the values.
The 750-455/040-000 represents a 4–20 mA signal, where the raw value is always positive. For that reason, it is represented as a word.
Hope this helps.
Use a UNION and you can satisfy both.