Modbus TCP
Like OPC UA, the Modbus integration runs in process inside cms-api.
Connection
Register the device under External Connections: host, port and unit ID.
Collection — MODBUS_TRIGGER and MODBUS_POLL
| Type | Behavior |
|---|---|
MODBUS_TRIGGER | Watches a register and fires when the value changes |
MODBUS_POLL | Scans registers on a schedule and produces a message per read |
Use trigger when the PLC signals an event; use poll when you need to sample values periodically (temperature, counters).
Delivery — MODBUS_WRITE
Writes to registers from the message data, also protected by the write permission gate — which, configured and unable to query the equipment, refuses the write instead of releasing it.
Modbus has no authentication and no rich types: a wrong address writes to the wrong place without complaining. Validate the register map in the simulator before pointing at real equipment.
Testing without hardware
The Simulators screen ships a built-in Modbus TCP server, with its own tag profiles.
A dropped connection raises the CONEXAO_MODBUS_PERDIDA alert.