Can the Uno handle two serial port functions ?

Using Arduino Networking, Protocols, and Devices
32

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For what it is worth, the RJ connector on the Serial device has the following
pinout as referenced by the device:

Pin1 - RS232 In
Pin2 - +12V
Pin3 - RS232 Out
Pin4 - Gnd

Don't you think this might mean that pin 1 is the receiving pin? If that's true, you have to connect T1OUT to pin 1 of this connector and R1IN to pin 3 of the connector. I would try to measure the pins before connecting to avoid producing a short circuit.

It is connected correctly as I don't get the serial from the panel T1OUT to pin 1 of this connector and R1IN to pin 3 of the connector ... I tried it just to make sure.

On another note, I was successful in reading and writing to the control panel with a USB2Serial converter which I built an interface to the RJ4 connector...

Must be something in the way the serial port & USB are shared on the Arduino that keep me from reading and writing to the control panel...

thanks for your help