Issue
Debugging SpaceLogic MP and RP controllers Modbus RTU
Product Line
EcoStruxure Building Operation
Environment
- Building Operation Multi-purpose Controller
- Building Operation Multi-purpose VAV
- Building Operation Room Controller (RP-C)
- Building Operation RP-V VAV
- Building Operation EZLogic RP-C
- Building Operation EZLogic RP-V
Cause
There is no packet data can be logged or viewed for Modbus MP and RP controllers and RP controller has no transmit and receive LEDs for the Modbus and no packet data can be logged or viewed. Article Modbus in the MP and RP Controller Introduction provides information on the differences between the Automation Server and MP and RP controllers Modbus operations.
Resolution
There are a couple of options, but they involve using another device connected to the Modbus network to view the packets
- Use a PC based Modbus slave simulator
- Use an Automation Server set up as a Modbus RTU slave, the packets can be sent to the trace log then viewed in the usual way.
Note: A defect with v3.2.1 EBO means this solution cannot be used to monitor a Modbus RTU bus because the AS replies to all requests and may cause conflicts on the network. All versions 3.1.2 and earlier work fine, as well the EBO 2022 (v4.0.1) as detailed in the Known Issue Modbus Slave incorrect response - Can use Picoscope to perform Serial Decoding for Modbus RTU as detailed in Picoscope Configuration for Modbus RTU capturing and decoding
