Serial modus Communication error Temperature sensor with RS485

I'm trying to read the temperature sensor (Pt1000) value from Node-RED.

Connection: The Pt1000 sensor is connected to a digital converter, which converts the readings into digital values. The converter is connected to the RS485 socket of the Revolution Pi (running Raspbian OS). I tried to read the value but encountered an error.
refer attach picture.




HI, im not to sure about your setup but im sure /dev/ttyAMA0 are the RX and TX pins on the GPIO of the PI, your are refering to a RS485 port on a PI, have to connected to the corect port ?

Have you used a thirdy party program like Modpol to verify the Modbus Slave works as you expect?