RS232 and GPIO Connector

The RS232 port can be used to feed the SOUND4 device with RDS UECP commands.

Only the RXD/TXD signals are used for UECP, there is no handshaking : the CTS/RTS are not used

Connector

Pin	Function	Direction
1	GND	Ground
2	RS_TXD	Out
3	RS_RXD	In
4	RS_RTS	Out
5	RS_CTS	In
6	GPI8	Opto isolated Input
7	GND	Ground
8	GPI6	Opto isolated Input
9	GPI5	Opto isolated Input
10	GPI4	Opto isolated Input
11	GPI3	Opto isolated Input
12	GPI2	Opto isolated Input
13	GPI1	Opto isolated Input
14	GPOCOM	Common GPO rail
15	GPO1	Solid State Relay
16	GPO2	Solid State Relay
17	GPO3	Solid State Relay
18	GPO4	Solid State Relay
19	GPO5	Solid State Relay
20	GPO6	Solid State Relay
21	GPO7	Solid State Relay
22	GPI7	Opto isolated Input
23	GPO8	Solid State Relay
24	GPICOM	Common GPI High-side rail
25	GP5V	+5V (Out), Fuse protected (100mA)

RS232

The DB25-M GPIO+RS232 is compatible with the V.24 standard, "DTE" side, meaning that it's the same as a computer-side connector.

Consequently when connecting a computer to the SOUND4 device, you have to use a Null Modem (cross cable).

So if your PC COM is male SUBD-9, the connection must be at minimum :

• PC COM DB9M TXD (pin 3) must go to (pin 3) DB25M RS_RXD
• PC COM DB9M RXD (pin 2) must go to (pin 2) DB25M RS_TXD
• PC COM DB9M GND (pin 5) must go to (pin 1) DB25M GND

(see Null_modem wiring diagram)

(Optionally other V24 signals can be connected (CTS, RTS, CD, DSR, DTR) so a fully wired branded Null-Modem cable or adapter should work)

Notes :

• the RS232 output voltage is approx. ±6V. Full ±12V is accepted at input.
• the output RS_TXD pin is not active (so is 0V instead of +6V) until there is activity on RS_RXD pin.