Special Interfaces - ASCOM Ascotel 2025 System Manual

7.5

Special Interfaces

4
7.5.1 V.24 Interface
V.24 Standard
V.24 is a serial interface used for connecting a printer or PC. In accordance with
the V.24 recommendation, a cable length of 15 m limits the transmission speed
to 38 400 bit/s. The system's maximum transmission speed is 115,200 bit/s. The
cable length must not exceed 2 m. Transmission errors can occur if these limits are
exceeded. A current loop converter (TTY) has to be used if the cable length is
insufficient. Cable lengths of up to 1 km are possible with this interface.
Two types of equipment can be connected to the V.24 interface:
• DCE: Data Communication Equipment
• DTE: Data Terminal Equipment
The pin assignment differs according to the type of equipment used.
Signals are specified as follows:
Tab. 4.45: V.24 signals
Signal Pin
D-Sub-9
TXD 3
RXD 2
RTS 7
CTS 8
DTR 4
DSR 6
DCD 1
SGND 5
A straight connecting cable (modem cable; uncrossed) must be used when con-
necting DTE-type equipment with DCE-type equipment (e.g. PC ® modem,
modem ® PC).
HBT_20321104_04/B0_en
Signal direction
D-Sub-25 DTE
2 out
3 in
4 out
5 in
20 out
6 in
8 in
7 —
ascom Ascotel 2025/2045/2065
CCITT stand-
ard V.24
DCE
in 103
out 104
in 105
out 106
in 108
out 107
out 109
— 102
Cabling Interfaces
Name / function
Transmitted Data
Received Data
Request To Send
Clear To Send
Data Terminal Ready
Data Set Ready
Data Carrier Detect
Signal Ground
4.73