MDS 05-3628A01, Rev. B
MDS 4790M (MPT 1411) I/O Guide
19
Diagnostics
A 9-pin, D-type port on the radio’s rear panel provides system diagnostics
information. The
DIAGNOSTIC PORT
is used to control and perform
diagnostics on the radio system from a connected computer. The
communication speed between the computer and radio is 9600 bps.
Figure 14 shows the EIA-574 (9-pin EIA-232) pin functions of the
DIAGNOSTIC
PORT
as viewed from the radio’s rear panel. Connection to J1 can be made with
a DB-9 male connector, available from many electronics distributors.
Invisible place holder
Figure 14. J1 Pin Connections
Analog Orderwire
You can plug an ordinary telephone handset into the jack on the rear panel to
communicate with someone on a handset plugged into another radio. Handsets
are available from GE MDS (P/N 12-1307A01).
Normal system operation is unaffected if all you do is listen over the handset.
When you speak into the handset, transmit audio is applied to an automatic
voice-operated transmit keying (VOX) circuit, keying the transmitter. At the
same time, the VOX circuit switches off external transmit data, interrupting the
normal flow of data in the system. Transmit audio from the handset is then
applied to the transmitter. Your voice can then be heard through a handset at
the remote radio. Since any noise over the handset interrupts transmission, you
should unplug the handset when it is not being used.
Alarm Contacts and Battery Back-up Connections
J10 is a plug-in terminal strip that provides connections for optional alarm circuits.
Figure 15 shows the function of each terminal as viewed from the rear panel.
Terminals 1 and 2 provide relay contacts that close when a minor alarm is
encountered. Terminals 3 and 4 provide relay contacts that close when a major
alarm is encountered. These relay contacts may be remapped if necessary
(switched from minor to major alarm outputs, or vice versa). The
ASENSE
command is used to change the relay contacts from normally open (
NO
) to
normally closed (
NC
).
The contacts are rated for 1 ampere at 60 Vac or Vdc.
PIN 2— RXD
PIN 3— TXD
PIN 4— +5 Vdc
PIN 5— GROUND
PIN 7— RTS*
* Used when reprogramming the radio firmware with a PC.
UNUSED
UNUSED
UNUSED
UNUSED
