Modbus RTU Terminal Connection Port
Terminal Connector
The main physical characteristics of the Modbus RTU port are:
| Physical interface | Multipoint 2-wire RS 485 – electrical networking |
| Connector | Screw terminal connector |
Wiring Diagram
Terminal Assignment
The table lists the terminal assignment for the Modbus RTU port.
| Terminal | Description |
|---|---|
| D0 | Data - |
| D1 | Data + |
|
Blank |
Not connected |
| Shielded earth |
Wiring Characteristics
Modbus RTU cable must be a shielded twisted pair cable.
The following table describes the characteristics of screw terminals:
|
Pitch |
5 mm |
0.2 in. |
|
Tightening torque |
0.2 N•m |
3 lb-in |
|
Flat screwdriver |
3 mm |
0.10 in. |
Port Settings
The Modbus RTU port has the following configurable settings:
|
Setting |
Setting range |
Default setting |
|---|---|---|
|
Node address |
1–247 in step of 1 |
1 |
|
Parity |
|
Even |
|
Baud rate |
|
19200 bps |
|
Timeout |
1–60000 s in step of 1 s |
1 s |
|
Endianness |
|
Big-endian |
The Modbus RTU port settings can be configured using the following interfaces:
-
A PC running the TeSys Tera DTM embedded in a FDT container, such as SoMove software
-
The LTMTCUF control operator unit
-
A PLC or DCS via the communication protocol