Motorola MVME1603, Installation And Use Manual, Page: 194 / 222

EIA-232-D Connections
C-4
C
Notes
1. A high EIA-232-D signal level is +3 to +15 volts. A low level
is
−
3 to
−
15 volts. Connecting units in parallel may produce out-
of-range voltages and is contrary to specifications.
2. The EIA-232-D interface is intended to connect a terminal to a
modem. When computers are connected without modems, one
computer must be configured as a modem and the other as a
terminal.
Interface Characteristics
The EIA-232-D interface standard specifies all parameters for serial binary
data interchange between DTE and DCE devices using unbalanced lines.
EIA-232-D transmitter and receiver parameters applicable to the
MVME1603/MVME1604 are listed in the following tables.
15 TxC
Transmit Clock (DCE). Output from modem to terminal; clocks data from the terminal
to the modem.
16 Not used.
17 RxC
Receive Clock. Output from terminal to modem; clocks input data from the terminal to
the modem.
18, 19 Not used.
20 DTR
Data Terminal Ready. Input to modem from terminal; indicates that the terminal is
ready to send or receive data.
21 Not used.
22 RI
Ring Indicator. Output from modem to terminal; indicates that an incoming call is
present. The terminal causes the modem to answer the phone by carrying DTR true
while RI is active..
23 Not used.
24 TxC Transmit Clock (DTE). Input to modem from terminal; same function as TxC on pin 15.
25 BSY
Busy. Input to modem from terminal; a positive EIA signal applied to this pin causes the
modem to go off-hook and make the associated phone busy.
Table C-2. EIA-232-D Interconnect Signals (Continued)
Pin
Number
Signal
Mnemonic
Signal Name and Description