Start main contents

  • Font Size
  • S
  • M
  • L


  • No : 23000
  • Release Date : 2018/09/03 17:31
  • Update : 2018/09/25 17:44
  • Print

Receiving back (echoing back) the same data sent from QJ71C24N

In 2-wire RS-485 communication of QJ71C24N(-R4), sent data is received back as it is. How do I prevent sent data from being received back?
Category : 


When data is sent from the RS-422/485 interface through RS-485 (2-wire type) communication and the same data comes back to RDA or RDB, we call it echo back.
The echo back function is enabled or disabled using any one of the following methods.

1. Using GX Works2
    Set "Various Control Specifications" of the intelligent function module utility.
2. Using GX Configurator-SC
    Make "CH2 Transmission control system setting".
3. Using a sequence program
    Set the following values for Echo back enable/disable setting (buffer memory address: 450 (1C2H)). (The default is 0.)

 - Setting value: 0 (Enable echo back)
    When sending data, QJ71C24N(-R4) receives back the data coming back thorough RDA and RDB.
 - Setting value: 1 (Disable echo back)
    When Sending data, QJ71C24N(-R4) does not receive back the data coming back thorough RDA and RDB.(The data is scrapped.)
Product Name
Network Related Products
Computer Link / Serial Communication
Did you solve your question?

If it is not resolved please ask from here.

Contact Us

May I have your opinion?