Appendix F; Rs-232C Interface Specifications - Multitech MultiModem MT2834MR6 User Manual

Appendix F

RS-232C Interface Specifications

The MT2834MR6's serial interface circuits have been designed to meet the electrical specifications in EIA
(Electronic Industries Association) Recommended Standard 232, Revision C (RS-232C). All signals
generated by the modem are approximately 10 volts when measured across a load of 3000 ohms or greater.
The receiving circuits of the modem accepts signals in the 3 to 25 volt range. The voltage thresholds are
defined as follows:
Negative: voltage more negative than 3 volts with respect to signal ground
Positive: voltage more positive than +3 volts with respect to signal ground
Signal Information
Binary State
Signal Condition
Control and Timing Function
The input impedances of all modem circuits that accept signals from the data processing terminal or CPU
equipment are 4.7KW. For more specific details, consult the EIA RS-232C standard. The following chart lists
the EIA RS-232C interface pins and circuits present on the MT2834MR6's RS-232C serial interface
connector. All other pins are unused.
Pin Multi-Tech
Assignment Designation
1 PG
2 TD
3 RD
4 RTS
5 CTS
6 DSR
7 SG
8 CD
9 +V
12 HS
15 TC
17 RC
20 TR
22 RI
24 XTC
25 OOS
* DTE = Data Terminal Equipment (terminal or computer)
DCE = Data Communications Equipment (the modem)
The computer or terminal should be supplied with a cable terminated with a Cinch DB25P or equivalent
connector mounted in a Cinch DB51226-1 or equivalent hood assembly as specified by the EIA RS-232C
standard.
Negative
One
Mark
Off
EIA Signal
Circuit Source* Circuit Function
— — Protective Ground
BA DTE Transmitted Data
BB DCE Received Data
CA DTE Request to Send
CB DCE Clear to Send
CC DCE Data Set Ready
AB — Signal Ground
CF DCE Data Carrier Detector
+V DCE Test Voltage
-- DCE High Speed
DB DCE Transmit Clock
DD DCE Receive Clock
CD DTE Data Terminal Ready
CE DCE Ring Indicator
DA DTE External Transmit Clock
CN DTE Terminal Busy
Positive
Zero
Space
On
Appendix
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