DMM
‐
4880 & DMX
‐
4880 Instruction Book
Revision 0
www.irtelectronics.com
Page 10 of 16
4880
‐
DMM_4880
‐
DMX_ib_Rev0.doc
DMX
‐
4880:
STM
‐
4 Input:
The optical STM
‐
4 input port on the rear of the unit is an SC/PC (standard) optical connector for use with single
mode fibre.
The standard optical detector used is a PIN detector and is rated for an optical input between
‐
3dBm and
‐
18dBm.
If the input signal strength is greater than
‐
3dBm an optical attenuator (5 or 10 dB recommended) must be used to
avoid overdriving the detector.
STM
‐
1 Outputs:
Four STM
‐
1 electrical outputs are provided as 75
Ω
output BNC connectors. Each STM
‐
1 output is equivalent to the
corresponding STM
‐
1 electrical input on the matching DMM
‐
4880.
Alarm Outputs:
Two relay alarm output states are provided via a phoenix style 3
‐
pin plug. Pin 3 is designated as Major, pin 2 is
designated as Minor, and pin 1 is ground. Both alarms are referenced to ground.
Alarm conditions are as follows:
Major switch to Open Circuit on no valid STM
‐
4 input present;
Minor switch to Open Circuit on no valid output STM
‐
1 streams present, or
no valid STM
‐
4 input present.
Both Major and Minor alarms switch to Open Circuit on power failure.
1 GND
2 MINOR
3 MAJOR
STM-1 O/P 3
ALARM O/P
DMX-4880
Rear Assembly Connections
STM-4 I/P
STM-1 O/P 2
SK 9 OUT3
PL4
SK10
SK 4 OUT4
SK 8 OUT1
SK3 OUT2
PL3
1
2
3
1-GND
2-MINOR
3–MAJOR
STM-1 O/P 1
STM-1 O/P 4
IRT
Communications
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