Specifications

MDS 05-3438A01, Rev. E MDS 4790/9790 Series I/O Guide 21
Diagnostics Connector—J1
A DB-9 (9-pin) connector on the 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 com-
munication speed between the computer and radio is up to 38400 bps.
Figure 19 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 elec-
tronics distributors.
Invisible place holder
Figure 19. Diagnostics Port Connector, J1
4-Wire Audio Connector—J2
J2 is a plug-in terminal strip that provides connections for 4-wire audio
circuits. Figure 20 shows the function of each terminal as viewed from
the rear panel.
Terminals 1 and 2 are for transmit audio input with a nominal 600 Ω
impedance. Terminals 3 and 4 provide a receive audio output with a
nominal 600 Ω impedance. Pins 5 and 6 provide a source for an external
keying source. Connecting pins 5 and 6 together keys the radio.
Figure 20. 4-Wire Audio Connector, J2
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
UNUSEDUNUSED
UNUSED
RECEIVE AUDIO
600 OHM
4123 5 6
TRANSMIT AUDIO
600 OHM
EXTERNAL KEYLINE
(GROUND TO KEY RADIO)