Service manual

DATA INTERFACE DESCRIPTION
A-3
April 2001
Part No. 001-9800-203
Output E U112-14 Not programmable and always the “Rx Data Call” function and active high (not available with data
and low tier models).
Output F U112-13 Not programmable and always the “Data CTS” function and active high (not available w/low tier).
Option 1 J301-9 Programmable as either an input or output.
Transmit W303/W313 This line is not programmable and is active high (high = transmitter keyed indication).
Table A-1 Data Interface Line Electrical Specifications (Continued)
Name Origin Description
A.3 SIGNAL FUNCTIONS
A.3.1 INTRODUCTION
Most of the input and output lines described in
the preceding section can be programmed for the func-
tions indicated in Table A-2. Low and mid tier models
have fewer functions available for each line than high
tier and data models. The programming of these input/
output lines is described in Section 4.9.
A.3.2 DEFINITIONS
The following terms are used frequently in this
section:
Asserted -
The state of an electrical signal when it
is active. The signal is “asserted” with active high
lines when the signal is high, and with active low
lines when it is low.
Released - The state of an electrical signal when it is
inactive.
The signal is “released” with active high
lines when the signal is low, and with active low
lines when it is high.
A.3.3 INPUT FUNCTIONS
The following are descriptions of the input
functions listed in Table A-2.
AUDIO MUTE - This input forces the radio to mute
microphone and speaker audio when it is asserted.
CALL GUARD - Conventional groups may be
programmed to utilize an external decoder. This signal
must be asserted to receive a call on one of these
groups.
CALL GUARD DISABLE - The asserted condition
disables both receive and transmit Call Guard squelch
on the selected system/group. Operation is the same as
when the CG Disable option switch is pressed (see
Section 3.9.5).
DATA ARQ - This signal is used in conjunction with
the DATA PTT signal to perform rapid channel turn-
around. Refer to Section A.4 for more information on
DATA ARQ operation.
DATA PTT - This input signal indicates that the
external device wants to access a data system and
group. The data group access function is performed (a
data group is found) and the system is accessed. If the
DATA ARQ function is programmed, it is used in
conjunction with the DATA PTT signal as described in
Section A.4.
When the transmission is complete (DATA PTT
released), the radio remains on the data system and
group until a normal operation causes it to move to
another system and group. Examples of normal opera-
tions include when scanning resumes due to the call
timer expiring and when the user manually changes
system or group. Note that once DATA PTT is
asserted, the normal microphone PTT signal is inhib-
ited until DATA PTT is released. In addition, the high
tier emergency function takes precedence over DATA
PTT.
DATA PTT REVERT - This input signal operates the
same as the preceding DATA PTT function except as
follows: As soon as the DATA PTT REVERT is
released, the radio immediately returns to the system
and group it was on when the DATA PTT REVERT
was first asserted. This function may delay data access
time.