Motorola 326X V.34 用户手册

Cabling and Interface Pinouts B-3

12

CI

112

Data Signal Rate 
Indicator

CI (112) is passed from modem to terminal, indicating signaling rate. 
When signal is on, modem operates at 2400 bps or greater. When 
signal is off, modem operates below 2400 bps.

13

—

110

Signal Quality

Signal passes from modem to terminal indicating signal quality of 
telephone line. When signal is on, signal quality is acceptable. When 
signal is off, signal quality is poor.

14

—

—

Ext Select

(All models.) Signal passed from terminal to modem to select between 
two option sets. Works in conjunction with Ext Select option.

(Models 3261/3263/3266/3268 only.) Signal passed from terminal to 
modem indicating whether to use a dial line or a leased line. When 
signal is on, modem uses a dial line. When signal is off, modem uses a 
leased line. This signal is used in Restoral mode only.

15

DB

114

Transmitter 
Signal Element 
Timing

Local modem sends an internally generated transmit timing signal to 
local terminal to synchronize transmitted data (TXD). See 
Clock=Internal.

16

—

117

Standby Indicator

(Models 3261/3263/3266/3268 only.) Signal passed from modem to 
terminal indicating type of line in use. When signal is on, modem is on 
a dial line. When signal is off, modem is on a leased line. This signal is 
used in Restoral mode only.

17

DD

115

Receive Signal 
Element Timing

Timing signal extracted from the received carrier. Local modem 
transmits this signal to the DTE to synchronize received data (RXD).

18

—

141

Local Analog 
Loopback Test

Initiated at local terminal and passed to local modem, causing it to 
initiate local analog loopback test.

19

—

—

—

Not used.

20

CD

108.1/
108.2

Data Terminal 
Ready (DTR)

108.1—Sent by DTE; causes the modem to connect to the phone line.

108.2—Sent by DTE; allows the modem to connect to the phone line.

21

—

140

Remote Digital 
Loopback Test

Signal initiated at local terminal and passed to local modem, causing it 
to initiate remote digital loopback test (V.54 Loop 2).

22

CE

125

Ring Indicator 
(RI)

Passed from local modem to local terminal. On during ringing, off 
between rings and when no ring received.

23

CH/CI

111/112

Data Signal Rate 
Select/Indicator

CI passed from modem to terminal indicating signaling rate. CI is set 
high for data rates greater than 2400 bps; otherwise, it is set low. CI is 
also set low while the modem is disconnected. The function of this pin 
is determined by the setting of rear panel Switch 1. CH (input) signal 
has no effect on modem operation.

24

DA

113

External Signal 
Element Timing

Transmit timing signal generated by some synchronous DTEs, 
providing clock to the local modem. See Clock=External setting.

25

—

142

Test Indicate (TI)

Local modem signals to local terminal when local modem is in test. 
The terminal can initiate a Busy Out condition on this circuit. The 
status of this signal is determined by the status of rear panel Switch 2 
and front panel option DTE Pin 25 configured for Test or Busy.