CTI Products CIB Comparator Interface - Manual (Page 12)

CIB Hardware Reference Theory of Operation
CTI Products, Inc.
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3.6 Operation With a Spectra-TAC Comparator
Some Motorola Spectra-TAC comparators with the "B" version Signal Quality
Module (SQM) can be damaged when a voltage greater than the comparator's
supply voltage is applied externally on the Disable input. (Motorola fixed this
problem in the "C" version SQM.) CIB modules shipped after January, 2003 are
shipped with E1B In, setting the input pull-up to +5 VDC.
Warning
Some "B" version SQM modules have a problem when they are inserted or
removed under power. Depending upon which pins connect first, the module may
be destroyed if there is an external connection to the Disable pin. The module
will try to power itself through the Disable pin and will destroy IC U3.
When inserting or removing the SQM from the comparator shelf, be sure to
first disable the module from the front panel switch on the SQM. This will
assure that the Disable input is grounded. After the module is re-inserted, turn off
the Disable switch.
3.7 Operation With a Digitac Comparator
Installation Notes
• A Digitac Comparator can be connected to a CIB module with a straight
through 50-pin cable. Jumper E1-A and E1 B must be out. See the CIB to
Digitac wiring chart. Be sure to set the Option Switches for Digitac
Comparator.
• The switches and jumpers on the CIB module are difficult to reach after the
module is mounted to the comparator. Always set the switches and jumpers
for the CIB module before installing it on the back of the Digitac comparator.
Fail & Disable
The Motorola Digitac Comparator drives its Fail/Disable line low when:
• A receiver input has failed (loss of status tone).
• A receiver is disabled from the switch on the front panel of the comparator.
In either of these two cases, the MCNRCD software will display a “FAIL”
indication on the PC.
The MCNRCD software will display a “DISABLE” when the receiver site is
disabled from the PC, since the CIB is generating the Disable signal..
Coded Mode
The Digitac "Mode" (Coded) outputs appear on CIB "Fail" inputs. When you set
the CIB switches to Digitac mode, the CIB module ignores the Fail inputs. If the
switches are set improperly, you will see a "Fail" indication whenever the Digitac
receives a Coded transmission.