Posted 15 Sep 2016 (edited) Greetings, I have L02CPU and LJ71C24 (for serial comm) and they act as a master. For slave I have some energy analyzer device. Device has a Half-duplex RS-485 serial interface (Modbus RTU protocol). Master only needs to read some data from slave. My question is: What protocol should I use for mentioned communication (MC, Predefined, Nonprocedural, Bidirectional)? I saw that if I use Predefined protocol I can select in Predefined Protocol Library, under the Manufacturer, Schneider Electric - MODBUS - 03: RD holding Registers. Is this OK for my type of communication? I will try to do some testing between LJ71C24 and QJ71MB91 (who will act as a slave), this or next week, but it would be helpful if someone can tell me correct protocol for my type of communication? P.s. I am using GX Works 2. Best regards, Luka Edited 15 Sep 2016 by Luka0204 Share this post Link to post Share on other sites
Posted 16 Sep 2016 Yes, You should use the pre-defined protocol and set-up the pre-defined protocol support function with a modbus request. Share this post Link to post Share on other sites
Posted 21 Sep 2016 I used Modbus from Schneider for predefined protocol and it worked. Gambit, thanks for the help. Share this post Link to post Share on other sites