Issue
Modbus TCP Device (Slave) address greater than 247
Product Line
EcoStruxure Building Operation
Environment
- Building Operation Enterprise Server
- Building Operation Automation Server (AS, AS-P, AS-B)
- Modbus TCP Network
- Modbus TCP Gateway
Cause
Modbus TCP Device (Slave) address 248 is reserved and cannot be used. (Modbus TCP Network or Gateway)
SmartStruxure supports up to address 247, as per StruxureWare Building Operation - Technical Reference Guide (up to v1.6.1).
There was a defect within v1.5.0 and earlier that caused address 250 to be used if the Device address is set to "Invalid." This defect was corrected in v1.6.1.
Resolution
From v1.9 this is corrected, so it is possible to define addresses for Modbus TCP devices from 1-247 and 249-254
Device addresses 0 and 248 are reserved.
Device address 255 is used as the Default address.
For Modbus RTU RS485 master/slave networks, slave device addressing is different, see KB article Modbus RTU slave address.
Further information about Modbus can be found in the KB article Modbus basics.
