I am trying to connect a Raspberry Pi to a OSDP card reader. The reader communicates via RS485, and is powered by 9-27V DC.
Unfortunately, I have not been able to succeed with a serial connection in any way. I have disabled serial debugging in Raspbian.
Seeing as I get no feedback from the software, I am looking to exclude the hardware as the issue. Can anyone see any flaws in the below solution? (I apologize for the child-like schematic)
If you can think if a better solution or think of any common pitfalls or ways to debug this, I'm all ears.
I power the system with a 12V DC power supply, and use a lm2596s buck converter to supply 5V to the Raspberry. I use a RS485 shield from AB Electronics to convert UART to RS485.
I tried what Andrew Malcolm suggested, and connected the UART pins for debugging. I do indeed receive an answer back, and it stops when disconnecting the pins. I conclude that the serial is setup correctly from this.