3
enable signal to the serial data transmitter on
the other
side
of
the
optical
link. When the timer is allowed to
run out (no more rising edges, meaning no more data),
this output will get no enable signals anymore and will
go into tristate, freeing up its line.
- Different dwell times may be used within the system.
Mixing hardware-tristate-detect
on
one side and dwell-
time on the other side is also feasible.
- The setting of tristate/dwell time in a unit does affect
the data fed into that unit, i.e. the way data is output at
the remote unit.
RS-485 line termination:
Line termination impedance
of interfaces D1 and D3 may be set to low (120
)
using dip switch 6 of bank S1 and S2, respectively
(table 3). Default is high impedance.
Audio port impedance:
Audio input impedance in the
ADS 1200 can be set by moving jumpers A (for audio
interface A1) and/or B (for interface A2) on the upper
circuit board (fig. 2). A jumper on pins 1-2 selects
high impedance for that port (default); shorting pins 2
and 3 lowers the audio input impedance to 600 Ohms.
3b)
Installation
Provide the units with power and connect appropriate
cabling (twisted pair for long electrical links).
Through-connecting the signal ground lines is
recommended. If SYNC problems occur after
powering up, check the optical link first.
4. Connector pin assignments
The electrical port pin assignments (table 5) are
such that similar ports of different units may be
connected back to back with reversed cable
(RS-232 interfaces excepted). See figure 5 for the
pin numbering convention used.
Pin
Port 1 (2)
Pin
Port 3 (4)
1
Audio in
+
1
RS-485/422 in
+ **
2
Audio in
-
2
RS-485/422 in
- **
3
GND
3
RS-232 in
4
CC1out b
4
RS-232 out
5
CC1in (ref. to GND) 5
GND
6
CC1out a
6
GND
7
Audio out
-
7
RS-485/422 out
-
8
Audio out
+
8
RS-485/422 out
+
Table 5. Electrical port pin assignments
** see note Figure 5
1
AUDIO1 IN +
AUDIO1 IN -
GND
CC1 OUT B
CC1 IN
(ref. GND)
CC1 OUT A
AUDIO1 OUT -
AUDIO1 OUT +
8
RS-485/422-1 IN +
**
RS-485/422-1 IN -
**
RS-232-1 IN
RS-232-1 OUT
GND
GN
D
RS-485/422-1 OUT -
RS-485/422-1 OUT +
1
8
Figure 5.
Socket pin assignments. The second port (A2/CC2) is
similar in layout to port A1/CC1/ while the downmost
port (D3/D4) is similar to the third (D1/D2).
Input connector pins marked ** also work as outputs in
2-wire mode (see text).
