Apologies for cross posting, but I have been chasing my tail for a few days now
I have a long standing project to build a front end consisting of an 20x4 LCD, an RS232 module and a couple of encoders - to connect to a TEN-TEC RX320/321.
The parameters for the RX320 are 1200 baud, 8-N-1
I've used pins 16, 17 for the ESP32 board.
a) I have tried the loopback test (write from Serial Monitor to ESP32 RX-TX looped) without the RS232 module - this works, the characters as typed are received and echoed on the Serial Monitor
b) Loopback test as above but with the RS232 in the chain, works as above
c) Connected the SerialMonitor+USB converter+ RS232 module and a very old laptop with a classic hardware Serial Port, I can exchange messages between the two devices- This is just to prove comms work between two devices (NO ESP32 here)
d) Same as above but with ESP32 - Serial Monitor+USB Converter+RS232 module + RS232module+ESP32 with LCD screen, works as follows, message typed on the Serial Monitor loopsback and is displayed on the Serial Monitor below as well as on the LCD screen
In the above I have ensured that wiring, code, written using SoftwareSerial.h or HardwareSerial.h works and wiring is correct.
Now coming to the problem
When the radio is switched on it sends a "DSP START" to the controlling device, actually a computer and the controller knows that it is ready to receive commands.
See [http://www.radiomanual.info/schemi/RX/T ... _guide.pdf](http://www.radiomanual.info/schemi/RX/T ... _guide.pdf)
When I connect the old antique laptop to the radio and set up Terminal with the correct parameters, I get "DSP START" displayed in the Terminal window, sending ? as required elicits the correct response from the Radio as VER100.
However, when I connect the radio to the ESP32, I get nothing, sometimes junk characters, but that's because I was playing around with the wires, but usually nothing.
What could I possibly be missing?
/StarKnight