Issue
- SLP Sensor Modbus RTU issue when used with RPC or AS
- Communication errors are seen during normal
- Values are updated very slowly, can take up to two minutes to populate/update the 15 objects within the SLP.
Product Line
EcoStruxure Building Operation
Environment
- Modbus RTU
- RPC Modbus
- Automation Server + Premium
- SLP SpaceLogic Sensors LSA_APP_REV2.03.19 and REV2.05.21
Cause
Once the Modbus communication is set up between RPC (or AS) and the SLP, although the values updates fairly regularly, multiple communication errors are also seen
The SLP read speed needs to regulated to prevent overwhelming it
The SLP Modbus transmission voltage is less than the AS
Resolution
Use with RP-C
- SLP struggles to respond to every request from the RP-C, changing the baud rate to 9600/19200 and increasing the "Silence characters" in the interface to 255 (maximum possible) should stabilize the communications.
- The character spacing cannot be adjusted enough in the RP-C to allow communication at 38400 or 76800
Use with AS/AS-P
- Adjust the “Poll point delay” in the Modbus Interface to 80ms
- The Silence characters and Transmit guard bits may also need to be increased
- Baud rate up to 38400 has been tested.
