Multi-Channel RS232 Port

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The DS1202 has four serial ports internally. The RS232 port of the DS1202 implements three outputs, four inputs, and one "spare" input (CD). Each of the three outputs can be used as a TX line of a serial channel, or as a control output such as RTS or DTR. Input lines can be used as an RX line of a serial channel, or as a control input such as CTS or DSR. The spare input cannot work as an RX line. This input is not used by the serial-over-IP application supplied by Tibbo and will be largely omitted from further discussion. Your Tibbo BASIC/C application can always use this extra input if you require it.

With three outputs and four inputs, the DS1202 can be said to offer 3.5 serial "channels". We say "3.5 channels" and not "four channels" because one channel will only have RX line and no TX line (remember, there are four inputs but only three outputs).

 

ds1202_conns

 

Mapping option

Available signals

Pins on the DB9M connector of the DS1202-RS

Missing

line

#2

#3

#8

#7

#6

#4

#9

Option 0

RX/TX/CTS/RTS/DSR/DTR

RX

TX

CTS

RTS

DSR

DTR

---

---

Option 1

RX/TX/CTS/RTS/DSR/DTR + RX/tx

RX

TX

CTS

RTS

DSR

DTR

RX4

tx4

Option 2

RX/TX/CTS/RTS + RX/TX + RX/tx

RX

TX

CTS

RTS

RX3

TX3

RX4

tx4

Option 3

RX/TX/CTS/RTS + RX/TX/CTS/rts

RX

TX

CTS

RTS

RX3

TX3

CTS3

rts3

Option 4

RX/TX/CTS/RTS + RX/TX/DSR/dtr

RX

TX

CTS

RTS

RX3

TX3

DSR3

dtr3

Option 5

RX/TX/DSR/DTR + RX/TX + RX/tx

RX

TX

RX2

TX2

DSR

DTR

RX4

tx4

Option 6

RX/TX/DSR/DTR + RX/TX/CTS/rts

RX

TX

RX2

TX2

DSR

DTR

CTS2

rts2

Option 7

RX/TX/DSR/DTR + RX/TX/DSR/dtr

RX

TX

RX2

TX2

DSR

DTR

DSR2

dtr2

Option 8

RX/TX + RX/TX + RX/TX + RX/tx

RX

TX

RX2

TX2

RX3

TX3

RX4

tx4

Option 9

RX/TX/CTS/rts + RX/TX + RX/TX

RX

TX

RX2

TX2

RX3

TX3

CTS

rts

Option 10

RX/TX/DSR/dtr + RX/TX + RX/TX

RX

TX

RX2

TX2

RX3

TX3

DSR

dtr

Option 11

RX/TX/CTS/RTS + RX/tx/CTS/RTS

RX

TX

CTS

RTS

CTS4

RTS4

RX4

tx4

Option 12

RX/TX/CTS/RTS + RX/tx/DSR/DTR

RX

TX

CTS

RTS

DSR4

DTR4

RX4

tx4

Option 13

RX/TX/DSR/DTR + RX/tx/CTS/RTS

RX

TX

CTS4

RTS4

DSR

DTR

RX4

tx4

Option 14

RX/TX/DSR/DTR + RX/tx/DSR/DTR

RX

TX

DSR4

DTR4

DSR

DTR

RX4

tx4

 

"Available signals" column shows a particular combination of I/O lines for each option. For example, option 0 defines the standard serial port arrangement with RX, TX, CTS, RTS, DSR, and DTR lines. Option 2 gives you one channel with RX, TX, CTS, and RTS lines, one more channel with just RX and TX lines, and yet another channel with a single RX line. The TX line is "missing" because, once again, there are only three outputs available. This is why this line is shown in grey lowercase (tx).