Verilink 2048 (34-00179) Product Manual - Manual (Page 15)

2-8 Installation 2048 PMU/NTU
the chassis without rewiring the communications bus. Com-
munications are restored by shorting contacts on the back-
plane when a slot is vacant.
NOTE: Ensure that Switch S2 is set to the ‘ RACK ’ posi-
tion (refer to Section 2.5.4 on page 2-3).
2.9 Alarm Connection
The stand-alone unit and the chassis modular unit provide
rear panel alarm relay contacts. These dry (isolated) alarm
contacts permit connection to a remote indicating device.
2.9.1 Stand-alone Unit
The connection for the stand-alone unit is made on pins 5
and 6 of the Alarm/Power connector as shown in Table 2-1.
Table 2-1 Alarm/Power Connection
Pin 5 is configured to operate in either a normally open
(NO) or normally closed (NC) mode as determined by the
setting of the alarm relay jumper shown below. Jumper J18
is located on the circuit board.
‘NO’ and ‘NC’ refer to the contact’s relationship to the
common contact under a ‘no alarms’ condition. Move the
jumper to NC for normally closed operation (opens on
alarm) or to NO for normally open operation (closes on
alarm). Make connections to the contacts using 20-gauge
stranded wire (or similar). Contacts are rated at 0.3 Amp
AC or 1.0 Amp DC.
2.9.2 Chassis Assembly
Alarm conditions from all modules in the chassis are bused
together in parallel and are presented on a single set of
alarm relay contacts which permit connection to a remote
indicating device. When connected, Pins 3 and 4 on terminal
strip TB1 operate in a normally open mode. Refer to the
1051-2 Chassis Configuration Guide for more information.
NOTE: All modules in a common chassis must use the
normally open contact mode.
Make connections to the alarm contacts using 20-gauge
stranded wire (or similar). The contacts are rated at 120 mA
AC or 120 mA DC.
2.10 Power Connection
The stand-alone unit and the modular chassis unit require a
-48 VDC power source that is capable of supplying 75 mA
current. Power supplies are available from TxPORT and are
listed in Table 1-1 on page 1-4.
Connect the ground lead before applying power
to the unit.
2.10.1 Stand-alone Unit
The power source is connected to pins 1 and 3 of the Power
and Alarm terminal as shown in Table 2-1.
Connect a chassis ground lead (18- to 20-gauge is recom-
mended) to the ‘Frame Ground’ terminal (pin 4). Connect
the other end of this lead to an appropriate facility ground.
Often, the 48 VDC return is also ground. In that case, both
return and ground leads should be connected to ground.
Connect the -48 VDC lead to the ‘-48 VDC’ terminal (18-
to 20-gauge recommended). Connect the return lead to the
‘48 VDC return’ terminal.
When power is applied to the unit, the front panel indicators
flash for approximately 10 seconds as the unit executes a
self-test function. If an ambiguous configuration has been
programmed, the front panel indicators will continue to
flash after the self-test is completed. If the unit is correctly
configured, the green ‘STATUS’ indicator on the front panel
should light.
2.10.2 Chassis Assembly
When operating the 2048 in the 12-slot chassis, all units are
powered by -48 VDC sources which are connected to the 6-
position terminal strip TB2 on the rear of the chassis. The
chassis is designed with two power buses. The ‘A’ bus feeds
the odd slots (1, 3, 5, 7, 9, and 11). The ‘B’ bus feeds the
even slots (2, 4, 6, 8, 10, and 12).
Pin Function
1 48 VDC return
2 Signal Ground
3 -48 VDC
4 Frame Ground
5 Alarm Contact
6 Alarm Common
J18 NO
NC
ALM
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