Schneider TSX17 serial communication upgrade and replacement

Tx Active: Sending in progress

Rx Buffer Full: The receive buffer is full

Timeout: timeout occurred

Parity Error: Parity check error

Frame Error: Frame format error

In addition, Command Words can be used for proactive intervention:

Force switch to fallback position

Suspend the ongoing exchange

This is very useful when dealing with communication deadlocks or device exceptions. For example, when the slave does not respond, the current request is terminated through a command word and the communication line is reset.

Modbus/Jbus protocol support

Both TSX SCG 1131 and TSX SCG 1161 modules support Modbus/Jbus protocol, which is one of the de facto standards in the field of industrial automation.

3.1 Master and Slave Modes

The module can be configured as a master or slave:

Master station mode: initiates communication requests proactively, reads or writes data from other slave station devices (such as frequency converters, instruments, HMI).

Slave mode: passively responding to requests from the master station, commonly used to integrate TSX 17 as a sub device into larger monitoring systems.

When configured in half duplex character mode, the module can also directly handle custom protocols, but Modbus is more standardized.

3.2 Data exchange process

Within the PLC, data tables are exchanged between the PLC and modules through text blocks, and the modules are responsible for converting this data into Modbus/Jbus messages. This process is transparent to PLC programmers: just fill the data to be sent into the specified table, then call the text function block, and the module will automatically complete the protocol encapsulation.

Typical application: TSX 17 serves as a slave station, providing current production, fault codes, temperature values, etc. to the upper computer; Or as a master station, read the values of multiple Modbus instruments.

Note: In Modbus/Jbus mode, the data length of one frame is also limited by 30 bytes, but more data can be obtained by reading multiple frames (such as reading multiple registers with function code 03).

UNI-TELWAY bus connection

UNI-TELWAY is an early fieldbus introduced by Schneider Electric, which is based on master-slave or token mechanism and supports multi station communication. TSX 17 can be connected to UNI-TELWAY in two ways:

4.1 Method 1: Using the TSX 17 ACC5 adapter module

Connection path: Terminal Port of TSX 17 → TSX 17 ACC5 → UNI-TELWAY bus

Role limitation: At this time, TSX 17 can only act as a slave and cannot initiate communication proactively.

Applicable scenario: Simply from the station device, such as only reporting data without reading from other stations.

4.2 Method 2: Through TSX SCG 1161 communication module

Connection path: Insert TSX SCG 1161 into the I/O bus expansion slot of the PLC → Connect cable through TSX CSC 015 → TSX SCA 62 user socket on UNI-TELWAY bus

Flexible role: TSX 17 can serve as a master or slave.

Key points of hard connection: When making a "T-shaped tap" on the UNI-TELWAY bus, a dedicated dual channel user socket TSX SCA 62 must be used, and wires cannot be directly connected in parallel.

4.3 Server and Client Mode

In the UNI-TELWAY network, TSX 17 can simultaneously act as both a server and a client:

Server: receives service requests from other clients in the network (such as reading/writing internal variables, starting/stopping PLC), executes them, and returns a confirmation. The client requests access through UNI-TE.

Client: Actively sends requests to other servers, such as reading data from remote stations, writing commands, or remotely controlling RUN/STOP. This requires the use of text function blocks to construct requests.

This bidirectional capability allows TSX 17 to serve as both a data acquisition station and a control master station, adapting to complex network topologies.

Attention: Regardless of which method is used to connect UNI-TELWAY, TSX 17 must be equipped with the corresponding version of PL7-2 language card:

Connected through ACC5: requires TSX P17 20 FA/FB/FC2/FD2

Connected through SCG 1161: requires TSX P17 20 FC2/FD2

PL7-2 Software Configuration Detailed Explanation (Practical Steps)

For on-site engineers, correctly completing communication initialization is a prerequisite for stable system operation. Taking TSX SCG 1131 as an example, typical configuration steps are given below.

5.1 Construction of Configuration Table

Define an 8-character table (e.g. named 'COMVNet') and fill in the following in order:

Example value of word offset content (Modbus slave, 9600/8/N/1)

Function code 02 (Modbus/Jbus slave)

Data bit 08

2 parity check 00 (none)

3 Stop Position 01

4 baud rate 05 (9600 bps)

5 send back display 00 (disabled)

6 receive feedback 00 (disabled)

7 reserved/spare 00

Baud rate code reference: 03=4800, 05=9600, 06=19200.

5.2 Initialization program segment

Use text function blocks (such as TET1) to send the configuration table to the module. Usually executed once in the first scanning cycle of the PLC (through the contactor flag).

5.3 Sending and Receiving Data

Send data: Fill up to 30 bytes into the source table, call the TEXT block, and select "Send with timeout confirmation" as the request code.