MXD5U OPERATIONS AND MAINTENANCE
2.4.3 Remote Status Outputs
There are only two remote statuses available to the operator, these being transmitter ON and an Error status. In the
table of remote signals, all remote status have a RS_ prefix.
The transmitter ON status is a relay contact that with one side of the contact connected to ground. When the
transmitter is in the ON state, this relay closes providing a path to ground to the RS_TXON signal. Thus when this
status sinks current to ground, it indicates that the transmitter is ON.
The transmitter Error status is also an active low current sink to ground, but is implemented with the output transistor
of an opto-isolator as shown in the diagram below. When the transistor sinks current to ground, it indicates that there
is some fault condition with the transmitter. This fault is an indication to the operator that there is some problem with
the transmitter (such as a VSWR trip, Interlock open or Power supply problem) that needs some attention. A ground
reference pin is provided at pin 12 to ease the interface task since all these remote commands are active low and
require a short to ground.
The Error status is a current sinking open collector output that comes directly from the NPN transistor outputs of the
opto-isolator devices. The available output sink current is dependent on the opto-isolator transfer ratio. Generally,
one can expect at least 20mA of sinking current for each output listed here. Because these are open collector, they
can be connected to maximum 30 VDC output. The active (true) condition whether high or low will depend on the
specific status output.
Figure 6 Remote Status Outputs
2.4.4 External1
Interlock
There is a pair of terminals on the D-connector that is used for an external interlock to interface to any site alarms or
shutdown conditions. These pins would expect a dry contact that is closed when there is no error condition. This
External #1 interlock is in parallel with the two pin terminal block on the rear of the transmitter chassis. The
transmitter applied its own +12V to one side of this interlock (the Ext1+ line) and will sense this +12V on the other
interlock side (the Ext1- line).
REMOTE SIGNAL
PIN#
DESCRIPTION
RC_TXON
1
Control,
Transmitter
ON
RC_VSWRRst
2
Control,
VSWR
Reset
RS_TXON
3
Status,
Transmitter
ON
Spare
[Unused]
4
RT_FwdPwr
5
Telemetry,
Forward
Power
Spare
[Unused]
6
RT_CutBack
7
Telemetry,
Cutback
Voltage
(1/2
Scale)
Ext1-
8
External
Interlock,
Normally
Open
RC_TXOFF
9
Control,
Transmitter
OFF
Spare
[Unused]
10
PUB09-03 Rev 0 April 16, 2009
09-03-7
MXD5U Operations and Maintenance
