hi all. I need to use the MODBUS RTU. I can not use ethernet because the two PLCs have different IPs (design motifs). I am using the CM 1241 RS232 modules and do not know what type of null modem use. I tried with the basic configuration of 3-pin, 2,3 and 5 (2 and 3 crossed) but I have not been successful. Would have to use all pins except the 9? and few are crossed or bridged? you know the exact configuration? I have to say is the first time I taste a MODBUS RTU communication and I have no experience. Edit: I've solved the problem with this configuration. Now, I've another question. I want to send and receive another struct (sending struct and receiving struct are in the master and the slave and they are equal). Struct to send is "pedidos-trama" and the struct to receive is "portabobinas". What data would have to allocate data_add and data_len (MB_MASTER) with the example of the picture? thanks tintoretto
