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System cabling
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MDI/MDO interface
General
The four Miscellaneous Discrete Inputs (MDIs) are intended for customer usage. The
inputs can be used to collect status information from the 1645 AMC itself or from other
transmission or non-transmission equipment like power supply systems, intruder detectors
or fire detectors. The external remote power supply (FSP) box is managed through this
interface.
An MDI shall be considered active when resistance between external voltage source and
input is less than 100 Ω. An MDI shall be considered inactive when resistance between
external voltage source and input is more than 500 kΩ.
Floating MDIs and non-floating MDIs
The external physical interface supports four floating MDIs and four non-floating MDIs
simultaneously. The non-floating MDIs are not connected to ground. There is also no pin
sharing between the floating MDIs and the non-floating MDIs.
An MDI is active when it is supplied by an external nominal 24 or 48 VDC voltage. This
causes current to flow through the diode part of the optocoupler and causes the opto
transistor to saturate. The saturated transistor pulls the GPIO signal to a logic "0". Each
MDI anode and cathode of the optocoupler are connected to the 25-pins Sub-D connector.
Figure 4-8 MDI circuit
MDI/MDO
CONNECTOR
DUAL OPTO-
COUPLER
MDI/MDO
CONNECTOR
The MDIs can be floating and non-floating with respect to system ground. Activation of
the floating MDI requires an external voltage in the range of 18-72 V (I
input). The non-floating MDI (Easy MDI or EMDI) does not require an external electric
voltage. It is recommended that the non-floating MDIs (EMDIs) are not externally
grounded.
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4-10
12
13
+
+
23
24
Alcatel-Lucent – Internal
Proprietary – Use pursuant to Company instruction
11
10
+
+
22
21
External cable installation
MDI/MDO interface
+3.3V
+3.3V
DUAL OPTO-
COUPLER
CKT
GRD
of 4mA by one
max
365-313-103R8.0
Issue 2 July 2009
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