Auxiliary (Aux) Connection; L-Band Buc Power Connection; Table 2–4. Buc Power Connector J11 Pin Assignment; Redundancy Connection - Datum Systems PSM-500 Installation And Operation Manual

PSM-500/500L/500LT SCPC Satellite Modem

2.3.4 Auxiliary (AUX) Connection

The modem has an auxiliary connector located on the rear panel, the 37-pin male "D" sub
connector J4. The pin-out of this connector is determined by option board(s) installed in the
modem; for example a multiplexer option would present overhead channel and analog channel
inputs at this connector. The pin definitions are defined in the addendum related to installed
options, for example when the IBS Multiplexer/Reed-Solomon option card is installed the I/O on
connector J4 is defined in Appendix RS.
2.3.5 L-Band BUC Power Connection/PSM-500L
The PSM-500L modem has a 5 pin circular DIN connector at the rear panel J11. This connector
is used to connect an auxiliary DC supply to power Block Up Converters that accept DC power
via the transmit line. This connector applies the input voltage to the transmit cable via a relay
internal to the modem and a "Bias-T" circuit. The relay is under processor control and can be
enabled or disabled using the front panel or remote control. The processor also reads the voltage
and current applied to the BUC and can create alarms in addition to reading voltage and current
at the front panel. The power connector pin-out and rear panel LED (labeled "BUC Power
Status") meanings are shown below.
Table 2–4. BUC
Power
Connector J11
Pin Assignment
J11 Pin #
1 Ground
2 Ground
3 V+
4 Ground
5 V+

2.3.6 Redundancy Connection

The modem is capable of operating in a limited 1:1 redundancy protection mode without the use
of a separate redundancy switch. It does require specific minimal facilities at the transmit and
receive IF signal connections and at the terrestrial data connection. These are a combiner at the
transmit IF, a splitter at the receive IF and a "Y" cable at the terrestrial data connection. With this
connection scheme the switching is only performed on the outputs from the modem. The modem
IF and data inputs are always available at the modem allowing internal circuitry to determine if
one modem is correctly accepting and "locking" to the input signals while the other is unable to if
in a failed state.
The two modems communicate with each other over the data "Y" cable. In this cable all
connections are 1 to 1 except the auxiliary RS-232 transmit and receive lines. These two lines
are swapped between the two modems allowing them to talk over an auxiliary serial link.
Specifics of this cable wiring are shown in Appendix C, "Cabling Specifications". Operation of the
data interface connected in parallel depends upon the programmable interface drivers to be tri-
stated and the receivers to be set in an un-terminated mode. This is accomplished under control
of the modem's internal software.
PSM-500/500L/500LT - Rev. 0.91
⇒
Only, 60 VDC maximum, 6 Amps maximum.
2
The power input is only intended for
4 5
positive voltages with respect to ground.
3
1
Connection
Red – No voltage sensed on DIN input
Green – Power sensed and enabled
Off – Power sensed but disabled
Caution: The BUC power input is DC
Rear Panel BUC Status Indicator
connector or power is input and enabled
but the cable to the BUC is shorted.
(connected) to transmit cable.
(disconnected) from transmit cable.
Installation
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