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© Sealevel Systems, Inc.
4021 Manual | SL9154 11/2021
Programming The ACB 56, Continued
Connector P4 Pin Assignments
RS-232 Signals
Signal
Name
Pin #
Mode
GND
Ground
5
RD
Receive Data
2
Input RS-232
CTS
Clear To Send
8
Input RS-232
DSR
Data Set Ready
6
Input RS-232
DCD
Data Carrier Detect
1
Input RS-232
RI
Ring Indicator
9
Input RS-232
TD
Transmit Data
3
Output RS-232
RTS
Request To Send
7
Output RS-232
DTR
Data Terminal Ready
4
Output RS-232
These Pin Assignments meet the EIA/TIA/ANSI-574 DTE Specification.
Please terminate any control signals that are not going to be used. The most common way to do
this is connect RTS to CTS and RI. Also, connect DCD to DTR and DSR. Terminating these pins, if
not used, will help insure you get the best performance from your adapter.
