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Hi, I am having some issues with Modbus and a temp controller. I think I am ok with daqfactory but very new to modbus. In the past I have used my own comms protocol over rs232 but now trying modbus over rs485. I have an omron K3SC-10 usb to rs485 converter and used this with a Yokogawa temperature controller absolutely fine. I used Modbus ASCII, found the registers in the manual and used the standard daqfactory commands to read holding S16 for each register. Surprisingly easy! I couldnt get hold of another yokogawa temp controller so bought an equivalent Omron E5CC model. Its running Modbus RTU and I have SD and RD traffic so everything is working comms wise. The manual wasn't so easy to understand so this took a while. My problem is that I just get modbus timeouts when I try to read any registers, sometimes I got some random (to me) data but then it stopped. I think this is because it doesn't recognise the commands I am sending? I found the quickmod program that you made (screenshot attached) and i can see some of the data I want: 248 is 24.8 degrees C! I don't really understand the tag number and number of points? Is tag the register? Is number of points trying to read an array or a range of registers?? I'm very confused but think I am close. I've attached the temp controller comms manual. I don't really understand about 2 or 4 byte modes and if the registers are in hex or what!? I think I have got as far as I can now using trial and error and very basic understanding but now maybe I need to actually understand what's going on! I'm ok with rs232 because you send it a command and it sends something back, simple conversation. I think modbus is the same, but I don't really understand the conversation between devices and the upper, GUI level isn't working for me. Maybe it's simple and you can explain what I am missing or if you have a suggestion for some easy learning material for me? I need to read the temperature controller PV and setpoint and write setpoints and PID values. Cheers Steve E5_C_CommunicationsManual_EN_201404_H175-E1-08 (1).pdf