User guide

ASCOM USER GUIDE
High Speed Base Band Modems
57
8.4.2 Module Link Settings
J1 – RS530 Circuit 103 (Transmit data) Circuit Termination – This link connects a 120 ohm load
resistor across the 103 circuit in position 1-3. This helps maintain signal rise times and
minimises reflections at greater than 9.6kbps over long lines. At lower rates and over short
lines the termination resistor may be omitted, (link set position 1-2).
J2 – RS530 Circuit 113 (External Signal Element Timing) Circuit Termination – This link
connects a 120 ohm resistor across the 113 circuit in position 1-3. This helps maintain signal
rise times and minimises reflections at rates greater than 9.6kbps over long lines. At lower
rates and over short lines the termination resistor may be omitted, (link set position 1-2).
J1
Interface Module -
Top View
J2
3
1
2
3
1
2
56 ASCOM USER GUIDE
High Speed Base Band Modems
8.4 RS530
8.4.1 25 Way D-type RS-530 Connector pin allocation
* Standards dictate that the control circuit 107 may be implemented as a balanced circuit
(using both A and B wires) or as an unbalanced single ended circuit. To allow inter-working
between balanced and unbalanced circuits, the A wire is to be used and the B wire is to be
joined to GND (circuit 102) at the receiver end of the circuit.
Pin Type SITS
Unbal A-wire B-wire Circuit Description 89/43
1 Earth/Shield Common
7,22, 102(AB) Common Return Common
10,13
2 14 103(BA) Transmitted Data Load
3 16 104(BB) Received Data Generator
4 19 105*(CA) Request to Send Load
5 (5) (13) 106*(CB) Ready for Sending Generator
6 (6) (22) 107*(CC) Data Set Ready Generator
8 (8) (10) 109*(CF) Data Channel Received Generator
24 11 113(DA) External Transmitter Signal Element Timing Load
15 12 114(DB) Transmitter Signal Element Timing Generator
17 9 115(DD) Receiver Signal Element Timing Generator
21 140(RL) Remote Loopback Load
18 141(LL) Local Loopback Load
25 142(TM) Test Indicator Generator
8