Appendix B - Rs-232C Interface Specification - Multitech DataTalker DT101 Owner's Manual

Appendix B - RS-232C Interface Specification

The DataTalker's RS232C interface circuits have been designed to meet the electrical
specifications given in the EIA (Electronic Industries Association) RS232C and ITU-T
(International Telecommunications Union) V.24 standards. All signals generated by the
DataTalker are approximately 10 volts when measured across a load of 300 ohms or greater. The
receiving circuits of the DataTalker will accept signals in the 3 to 25 volt range. The voltage
thresholds are:
Negative =
Positive =
SIGNAL INFORMATION:
Binary State
Signal Condition
Control and Timing Function
The input impedances of all DataTalker 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 DataTalker's
RS232C connector. All other pins are unused. The composite side of the DataTalker is configured
as a DTE device and the channel sides are DCE devices.
PIN MULTI-TECH
ASS DESIG
2 SD
3 RD
4 RTS
5 CTS
6 DSR
7 SG
B CD
9 +V
15 TC
17 RC
20 TR
22 Rl
24 XTC
25 OOS
*DTE =
DCE =
The computer 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
RS232C/V.24 standard.
voltage more negative than -3 volts with respect to signal ground.
voltage more positive than +3 volts with respect to signal ground.
NEGATIVE
One
Mark
Off
EIA CCITT
CIRCUIT CIRCUIT
BA 103
BB 104
CA 105
CB 106
CC 107
AB 102
CF 109
+V --
DB 114
DD 115
CD 108/2
CE 125
DA 113
CN 142
Data Terminal Equipment
Data Communications Equipment
Appendix B - RS-232C Interface Specification
POSITIVE
Zero
Space
On
SIGNAL
SOURCE*
DTE
DCE
DTE
DCE
DCE
——
DCE
DCE
DCE
DCE
DTE
DCE
DTE
DTE
CIRCUIT
FUNCTION
Transmitted Data
Received Data
Request to Send
Clear to Send
Data Set Ready
Signal Ground
Data Carrier Detector
Test Voltage
Transmit Clock
Receive Clock
Data Terminal Ready
Ring Indicator
External Transmit
Terminal Busy
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