Just curious what your thoughts are. I've used modbus for many years with industrial automation, and it's nice to see the implementation into Arduino. I've set up my arduino as a master and am using a CompactLogix PLC as a slave. There is some latency between the data transfers that doesn't typically exist in a normal modbus configuration. Wondering if anyone's played with this enough to get some quicker response out of it.
There is some latency between the data transfers that doesn't typically exist in a normal modbus configuration.
Can you be a bit more specific about that latency? What hard- and software do you use (Links)?
pylon:
Can you be a bit more specific about that latency? What hard- and software do you use (Links)?
You don't need RSLinx to use Modbus TCP. The programming software is RSLogix 5000, but that's irrelevant, too.
The processor (w/ embedded ethernet) supports Modbus TCP. I have the PLC setup as a slave and the Arduino as a master. For example, if I initiate a FC16 code to write multiple registers, lets say a count of 4, it might take 0.5 to 1 second for it to show in the PLC. For Modbus TCP, this is very slow. I'm trying to find the bottleneck.
You might sniff the network traffic to see how long the PLC needs to answer your command. If the response is received in a timely manner and the result is show success I would check the ModBus TCP implementation on the PLC. If the response is returned with the same latency or shows a failure, post your complete code to check that first.