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C5-E Modbus RTU/USB Online Manual

Commissioning Parent topic: Commissioning

Configuring via Modbus RTU

Described in the following chapters is how you can establish the communication.

The controller is set to slave address 1 ex works (rotary switch to "1"), baud rate 19200 baud, even parity, 1 stop bit. All changes take effect only after the controller is restarted.

Communication settings

Slave address, baud rate and parity are dependent on the position of the S2 and S3 rotary switches and, if applicable, on objects 2028h, 202Ah, 202Dh.

Configuration Object Value range Factory settings
Slave address 2028h 1 to 247 5
Baud rate 202Ah 7200 to 256000 19200
Parity 202Dh
  • None: 0x00
  • Even: 0x04
  • Odd: 0x06
 0x04 (Even)
The number of data bits is always "8" here. The number of stop bits is dependent on the parity setting:
  • No parity: 2 stop bits
  • "Even" or "Odd" parity: 1 stop bit

The following baud rates are supported:

  • 7200
  • 9600
  • 14400
  • 19200
  • 38400
  • 56000
  • 57600
  • 115200
  • 128000
  • 256000

You must save the changes by writing value "65766173h" in object 1010h:0Bh. The changes are not taken over until after the controller has been restarted.

Rotary switch

The C5-E is equipped with two hex coding switches – similar to that shown in the following figure.

You can set the source for the slave address, the baud rate and the parity using the combination of numbers from both rotary switches.

The following applies here: the combination of numbers is formed using rotary switches S2 and S3, where S2 represents the higher-value byte and S3 the lower-value byte

Example
Switch S2 is set to the value "0h", switch S3 to the value "Fh"; the result is the value "0Fh"="16d".
Switch S2 is set to the value "Ah", switch S3 to the value "1h"; the result is the value "A1h"="161d".
Number combinations of the rotary switches Slave address Baud rate and parity
dec hex
0 0 Object 2028h Object 202Ah or 202Dh
1-247 1-F7 Number of the rotary switches Object 202Ah or 202Dh
248-255 F8-FF 5 19200, even Parity

Establishing communication

  1. Connect the Modbus master to the controller via the RS-485+ and RS-485- (see X1 – Modbus RTU (RS-485) IN and OUT) cables.
  2. Supply the controller with voltage.
  3. Change the configuration values if necessary.
    The controller is set to slave address 1 ex works (rotary switch set to "1"), baud rate 19200 baud, even parity, 1 stop bit.
  4. To test the interface, send bytes 01 65 55 00 2E 97 to the controller (you can find a detailed description of the Modbus function codes in chapter Modbus RTU).
    The object dictionary is read out.
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