TM3 Modbus Serial Line Bus Coupler Presentation
The TM3 Modbus Serial Line bus coupler is a device designed to manage serial line communication when using expansion modules with a controller in a distributed architecture. The TM3 Modbus Serial Line bus coupler supports the TM3 expansion modules and the TM2 expansion modules.
The TM3 Modbus Serial Line bus coupler can be physically connected to the serial port of a master device and it must be declared under a logical node representing the Modbus Serial IOScanner of a device inside EcoStruxure Machine Expert.
The TM3 Modbus Serial Line Bus Coupler conforms as a Modbus slave.
The Modbus packet structure is as follows:
|
|
Modbus Messages |
||
|---|---|---|---|
|
Address |
Function Code |
Data |
CRC |
|
1 byte |
1 byte |
n-byte field |
2 bytes |
The Modbus RTU message frame is as follows:
|
Slave Address |
Function Code |
Data |
CRC |
|---|---|---|---|
|
1 byte |
1 byte |
0-252 bytes |
2 bytes CRC Low, CRC Hi |
Serial Line Boot-Up and Operating Mode
The following diagram shows the operating modes of the TM3 Modbus Serial Line Bus Coupler:
The following table describes the transitions during the boot-up process:
|
Item |
Description |
|---|---|
|
1 |
Device boot-up |
|
2 |
After boot-up, the device automatically enters the Unconfigured state. |
|
3 |
The device begins configuration process. |
|
4 |
The controller has taken control of the device. |
|
5 |
A timeout error occurred. |
|
6 |
A reconfiguration process is initialized. |
|
7 |
An unrecoverable error caused a system reboot. |
Serial Line Communication Configuration
The TM3 Modbus Serial Line bus coupler network interface configuration parameters are defined in the following table:
|
Parameter |
Value |
|---|---|
|
Mode |
RTU |
|
Parity |
EVEN |
|
Stop bit |
1 |
|
Data bit |
8 |
The list of supported commands is described in the following table:
|
Modbus Function Code: Dec Index (Hex) |
Sub-Function: Sub-Index |
Command |
|---|---|---|
|
3 (0003H) |
- |
Read n registers |
|
6 (0006H) |
- |
Write a single register |
|
16 (0010H) |
- |
Write n registers |
|
22 (0016H) |
- |
Mask write register |
|
23 (0017H) |
- |
Read/Write n registers |
|
43 (002BH) |
14 |
Read slave identification registers |
Serial Line Identification Objects
The Device Identification Modbus command returns the following objects:
|
Object ID |
Description |
Value |
Type |
|---|---|---|---|
|
0x00 |
VendorName |
Schneider Electric |
ASCII String |
|
0x01 |
ProductCode |
0x1109 |
|
|
0x02 |
MajorMinorRevision |
XYxy (MAJORminor) |
The TM3 Modbus Serial Line bus coupler supports slave address from 1 to 127, corresponding to rotary switch address settings. Using addresses outside of the slave address range may disrupt communications between other devices on that serial line.
