Questions to ask yourself
What’s the problem?
What’s happening?
What’s supposed to happen?
What have you tried?
What haven’t you tried?
Have you tried isolating each component?
Was it working before?
If so, did something change right before it stopped working? For example, power outage, firmware/hardware updates, re-programmed, new operator, etc.?
What software are you using? Is it the latest? Do you need the latest?
What firmware do you currently have installed?
Is the error repeatable or is infrequent?
Can you take a screenshot or capture short video of the error?
Are there any indicators LEDs? If so, describe their behavior, i.e. flashing, solid, from power-up to fault.
Is the unit or component too hot to touch?
Have you tried reinitializing and reprogramming the device?
Can you isolate the problem to a section of your program? If so, provide just that section of program. If not, provide the entire program.
Have you reviewed the latest datasheet for important information?
Wiring
Have you tried swapping loging wiring? Tx <==> Rx, RS-485A(+) <==> RS-485B(-)
If the I/O Pulled high vs pulled low.
What’s the minimum power supply voltage and worst case current draw? NPN (sinking) vs PNP sensor (sourcing) Is there a fuse present? Does it test good? If not, check potential wiring issues, shorts, broken insulation, conductive shavings, etc., before replacing fuse.