naturephoenix
Member
Hey ,
Can someone explain me what's programming difference in realisation of the modbus rtu regarding these 2 CPUs.
I have worked with s7-1200 and with CM in your program you just need in a case of modbus master to use 2 functions. One function you use once in OB100 and another you are using cyclic in OB1
First function is Mb_comm_load(OB100)
Second function is mb_master_fb (OB1).
I dont need to take care of the modbus protocol rules with s7-1200 modbus rtu solution.
My question is how this going with ET200s side cuz friend of mine told me here we have to deal with construction of MODBUS message. IS that true?
So with Et200s CPU and 6ES7-138-4DF11-0AB0 there are function S_SEND and S_RECEIVE.
Should I take care for modbus message rules? COnstantly send requests with S_SEND to 6ES7-138-4DF11-0AB0 and constantly listen incoming bytes with S_RECEIVE from 6ES7-138-4DF11-0AB0.
Or basically all has been resolved on its easy way with those two functions same as it is case with s7-1200 and CM RTU 485 module
Can someone explain me what's programming difference in realisation of the modbus rtu regarding these 2 CPUs.
I have worked with s7-1200 and with CM in your program you just need in a case of modbus master to use 2 functions. One function you use once in OB100 and another you are using cyclic in OB1
First function is Mb_comm_load(OB100)
Second function is mb_master_fb (OB1).
I dont need to take care of the modbus protocol rules with s7-1200 modbus rtu solution.
My question is how this going with ET200s side cuz friend of mine told me here we have to deal with construction of MODBUS message. IS that true?
So with Et200s CPU and 6ES7-138-4DF11-0AB0 there are function S_SEND and S_RECEIVE.
Should I take care for modbus message rules? COnstantly send requests with S_SEND to 6ES7-138-4DF11-0AB0 and constantly listen incoming bytes with S_RECEIVE from 6ES7-138-4DF11-0AB0.
Or basically all has been resolved on its easy way with those two functions same as it is case with s7-1200 and CM RTU 485 module