Multitech MULTI MODEM II MT5600BA - Manual (Page 106)

G Pin Descriptions
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MultiModemII User Guide
Appendix G: Pin Descriptions
RS-232 Pin Descriptions
Label Pin I/O type Signal name/description
CGND 1 GND CGND is tied common to GND on the modem’s PCB.
TD 2 Transmitted Data The DTE uses the TD line to send
data to the modem for transmission over the telephone
line or to transmit commands to the modem.
RD 3 Received Data The modem uses the RD line to send
data received from the telephone line to the DTE and to
send modem responses to the DTE.
RTS 4 Request to Send The RTS signal is used for hardware
flow control.
CTS 5 Clear To Send CTS is controlled by the modem to indi-
cate whether or not the modem is ready to transmit data.
CTS high indicates to the DTE that signals presented on
TD will be transmitted to the telephone line. CTS low
indicates to the DTE that it should not transfer data
across the interface on TD.
DSR 6 Out Data Set Ready DSR indicates modem status to the
DTE. DSR low indicates that the DTE is to disregard all
signals appearing on the interchange circuits except
Ring Indicator (RI). It reflects the status of the local data
set, and does not indicate an actual link with any remote
data equipment.
GND 7 GND Ground.
CFLO 8 CD Carrier Detect The modem uses the CD line to signal to
the DTE that a carrier has been detected.
+12V 9 A positive voltage output from the modem used for tests
or for strapping signals high if needed.
10 NC
11 NC
12 NC
13 NC
14 NC
TCLK 15 TC Transmit Clock Output from modem, used in syn-
chronous mode.
16 NC
RCLK 17 RC Receive Clock Output from modem, used in synchro-
nous mode.
V54-2 18 AL Analog Loop Input to modem to enable analog loop test.
19 NC
DTR 20 DTR Data Terminal Ready Input to modem from DTE to
control answering and disconnection of modem.