Owner`s manual

PN 88300150
4/3/01 94
Appendix H
RS232C Interface Specifications
The MT2834MR’s RS232C interface circuits have been designed to meet the electrical specifications
given in EIA (Electronic Industries Association) RS232C standards. 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:
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: NEGATIVE POSITIVE
Binary State One Zero Signal Condition Mark Space Control and
Timing FunctionOff On
The input impedances of all modem circuits which accept signals from the data processing terminal or CPU equipment have
DC resistances of 4.7K. For more specific details, consult the EIA RS232C standard itself.
The following chart lists the EIA RS232C interface pins and circuits present on the MT2834MR’s RS232C
Interface connector. All other pins are unused.
PIN MULTI-TECH EIA SIGNAL ASSIGNMENT DESIGNATION CIRCUIT SOURCE*
CIRCUIT FUNCTION
1PG ——Protective Ground
2 SD BA DTE Transmitted Data
3 RD BB DCE Received Data
4 RTS CA DTE Request to Send
5 CTS CB DCE Clear to Send
6 DSR CC DCE Data Set Ready
7SGAB— Signal Ground
8 CD CF DCE Data Carrier Detector
9 +V +V DCE Test Voltage
12 HS -- DCE High Speed
15 TC DB DCE Transmit Clock
17 RC DD DCE Receive Clock
20 TR CD DTE Data Terminal Ready
22 RI CE DCE Ring Indicator
24 XTC DA DTE External Transmit Clock
25 OOS CN DTE Terminal Busy
* 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
RS232C standard.