Hello,

Meezelmao

Hello! I have read a lot of topics on this forum, but I have not found a solution to the problem. When trying to initialize the modbus port, I get error 16 # 7000. In this case, the DONE bit at the first initialization is set to one, but then it is again transferred to FALSE. The error bit is not true. 
 I use 1215C DC/DC/RLY CPU (Firmware v 4.4) and CB 1241 board (v 1.0). TIA Portal V16 with 
 4.4V of MODBUS(RTU) lib. COMLOAD v 3.1 and MASTER v 3.3 with cleear project from example. What can i do wuth it? I set MODE to 4.

 I recommend for first read Help about your mentioned block. Then you can see that in STATUS values description some values with ERROR value indicate no error but only status. Check pls what your value indicate and you can then be sure you haven't error. In many topics is clear that output signals can be available only for one scan of CPU so you need monitor them in code to be sure all is working ok because after scan passed your value can be set to FALSE. Hope you understand why you set MODE to 4, simply read pls Help what each of parameters means and what values can be set.

Hello,

hard to answer because many other aspects can affect your functionality.

1. correct comm settings on both side (speed, data bits,...)

2. correct set of MODE (set of 2 wire mode) also in code, not only in HW Cm cfg. It needs to ne set prior execution of comm_load, not soon!

3. swap A/B lines on one of devices, not both.

4. correct sequence of code flow, first need comm_load correct DONE, then only start req for Master.

5. correct use of Master block parameters (register address, Slave address, data type definition, how much amount data require receive,...).

Really answer to your problem can be very long and unefective, I recommend check Forum for similar topics and learn what you need look for. No problem write here next problem in case you go further. Your error code can point to one of my mentioned points.

Simply do for first tests with some PC app connected to Slave device to be sure of functionality. With PLC only and without good experience you can have problems with no idea where it is.

 Hello,

Meezelmao

Now, i just change CB1241 to CM1241 and my data transmittion works right. All settings are same.

 that's really lucky for you because in case of what aspects can affect functionality (base module HW address, wire signals status, type of Cm and correct set of parameters instead of CB module) It's big surprise to me, really. Can you pls attach that code pieces and HW cfg screenshots in ZIP file?