Appendix B. CS I/O Connection

B.1 CS I/O 9-Pin Connection

The pin out of the connector is shown in Figure B-1. The direction of the signal relative to the modem is shown in parenthesis. Unless specified otherwise, all levels are 0 V for logic low, 5 V for logic high.

FIGURE B-1. CS I/O Pin Out

1.(input) +5 VDC supply. Not used by COM220.

2.(input) Ground

3.(output) Ring - a logic high signifies a ring signal has been detected

4.(output) RX Data - serial data from COM220

5.(input) Modem Enable - a logic high internally switches power to the modem. A logic low internally shuts off power to the modem.

6.(input) Serial Device Enable - a logic high disables communication with the modem without removing power or changing the modem's mode.

7.(input) SDC clock. .

8.(input) +12 VDC supply

9.(input) TX Data - serial data to COM220

B-1