Data Center Expert | When polling double registers, both registers must be polled together.
Issue:
When polling double registers in Data Center Expert, both registers must be polled together.
Product Line:
EcoStruxure IT Data Center Expert
StruxureWare Data Center Expert
StruXureware Central
InfraStruXure Central
Environment:
Modbus communications
Cause:
Modbus registers are limited to 16 bits, limiting the length of values they can store and return to a BMS. 16 bit registers cannot express a value greater than 65535. Because some values returned by a device's sensor may be exceed this limit, you may need to use a double register to express longer values. A double register uses two 16 bit registers together to express a 32 bit value. If you choose to configure 31001 as a double register, it will include 31001 and 31002.
Resolution:
When polling these registers, poll both 31001 and 31002 (or whatever register pair you have set up this way) as a single value during the same poll. Failure to do so will return invalid results.