Hi guys, Thank you for taking time out to look at this. I'll keep it short, trying to a very simple project with Modbus and Labview. I followed the NI tutorial here:http://www.ni.com/tutorial/13911/en/ This tutorial is for Modbus TCP but I adapted to RTU. I am just trying to set up a very simplistic gui as a master to write a bool to a coil, then read that coil value on a slave device. The slave will be physical but for now(testing) I have set up the populare simplymodbus slave gui found here: http://www.simplymodbus.ca/RTUslave.htm
I virtually paired comm ports to get my labview project to talk to the simlpy modbus slave VI. It works but I am having some apparent trouble. I think the challenge is fundamental to understanding what exactly is happening. I am able to write to the slave, change the value etc. However the value keeps flip flopping between read and write. For eg. when the VI starts, the first thing it does it READs the value, then writes 0 (bool switch is off). It keeps flip flopping between them until I write a 1. Now it will WRITE a 1 but then go back to READ, then WRITE. I have changed access modes to write accordingly, not sure whats happening. Please check attached screenshots.
Any help is appreciated. Thanks!
