The slave doesn't sent any message before the host requests it. The host systematically initiates the exchange and the 'slave' device answers. MODBUS messages correspond to relatively simple operations to read and write 16 bit words and binary registers often called 'coils'. MODBUS is a protocol between a host master and devices slaves to access the configuration of the devices and to read the measures. The main particularity when using RS is in the format of the exchanged data. It's cheaper and it's one less component in the system. Sometimes this means that you must screw a small resistance on a terminal, or simply move a switch in the adequate position.Īn RS bus is often made of just two wires and a resistor at the extremities RS and RS are not directly compatible: you must use the correct type of interface, or the signals won't go through. However, there is a small trick to do ?Ĭameras for vehicles at each end of the bus, you must put a bus terminator.

Therefore, you don't have to multiply RS interfaces on the host to question several devices. An important advantage of RS is that you can put several RS devices on the same bus. So here is a quick remedial course RS is a serial transmission standard, a little bit like RS, but using other electric signals. By mvuilleuin Internet of Things and Measuresaugust 21, While exchanging with our customers on the best ways to interface industrial controllers, we noticed that nowadays the small secrets enabling you to use an RS interface were sometimes unknown from engineers implementing computer or internet based automation.

Labview modbus examples