DATEREMOTE CDS-9020 Manual page 34

•
6 Data Set Ready
Name: CC
o
Direction: DTE <- DCE
o
CCITT: 107
o
On this line the DCE tells the DTE that the communication channel is available (i.e., in an automatic calling system, the DCE
(modem) is not in the dial, test or talk modes and therefore is available for transmission and reception). It reflects the status of
the local data set and does not indicate that an actual link has been established with any remote data equipment.
•
7 Signal Ground
Name: AB
o
Direction: -
o
CCITT: 102
o
This pin is the reference ground for all the other signals, data and control.
•
8 Receive Line Signal Detect or Data Carrier Detect
Name: CF
o
Direction: DTE <- DCE
o
CCITT: 109
o
The DCE uses this line to signal the DTE that a good signal is being received (a "good signal" means a good analog carrier,
that can ensure demodulation of received data).
•
A note on signal travel direction
The pin names are the same for the DCE and DTE. The Transmit Data (pin number
2) is a transmit line on the DTE and a receive line on the DCE, Data Set Ready (pin
number 6) is a receive line on the DTE and a transmit line on the DCE, and so forth.
• Electrical Signal Characteristics
•
Voltage levels defined in the standard
•
Data signals
•
•
Driver (Required)
•
Terminator (expected)
•
•
Control signals
•
•
Driver (Required)
•
Terminator (expected)
•
The Noise Margin Issue
Note that terminator (receiving end) voltages are not the same as driver required voltages. This voltage
level definition compensates for voltage losses across the cable.
"0","Space"
5 - 15
3 - 25
"Off"
-5 - -15
-3 - -25
34
"1","Mark"
-5 - -15 Volts
-3 - -25 Volts
"On"
5 - 15 Volts
3 - 25 Volts