Comtech EF Data SDM-2020 - Manual (Page 153)

SDM-2020 Satellite Modulator Revision 7
Data Interfaces MN/SDM2020M.IOM
12-6
Single ended open collector outputs (external pull-up resistor required) provide
indicated Modulator Faults (MF) and Demodulator Faults (DF). For MF and DF,
a fault is indicated by an OFF (Vout = Hi) open collector transistor and the
normal OK state indicates an ON transistor (Vout = Lo). MF and DF are routed
directly from the modulator or demodulator respectively. The characteristics of
these outputs are:
Voh = 12V maximum
Vol = 0.5V maximum at Io1 = 8 mA
A carrier detect (CD) output signal provides an indication that the demodulator is locked.
The output is TTL compatible. CD is routed directly from the demodulator. The default
state of the CD is high when the unit is locked, but the sense will be programmable
(function provided at the system level).
A Request to Send (RTS) input is provided to allow for remote control of the modulator
transmission carrier. The ability to enable/disable control of the modulator via this signal,
as well as the signal polarity, is programmed by the user (function provided at the system
level).
12.1.3.4.2 Auxiliary Interface Connector –J5
This port provides input/output of the modem-specific signals. The connector is
9-pin subminiature D female, with threaded jack nuts.
Table 12-4. Auxiliary Interface Connector –J5
Signal Function Name Pin # Type Comment
1 GND Signal Ground
Demodualtor Fault
Indicator DF 2 O Demodulator Summary Fault. Open Collector
Redundancy switch appplication
3 N/C
Request to Send RTS 4 I Modulator Request to send. TX control. TTL
5 N/C
Modulator Fault
Indication MF 6 O Modulator Summary Fault. Open collector.
Redundancy switch application.
Carrier Detect CD 7 O Demodulator. Carriewr detect. TTL
Legend: O = Output
I = Input
N/C = No Connection