DMU380SA Series
User’s Manual
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Doc# 7430-0026 Rev.01
Page 5
Do not reverse the power leads or damage may occur.
Serial Data Interface
2.4
The main serial interface is standard RS-232, 9600, 19200, 38400, or 57600 baud, 8 data
bits, 1 start bit, 1 stop bit, no parity, and no flow control and will output at a user
configurable output rate. Pins 3 and 5 are designated as the main RS-232 interface pins.
The secondary serial interface is also standard RS-232, 9600, 19200, 38400, or 57600
baud, 8 data bits, 1 start bit, 1 stop bit, no parity, and no flow control, and is used by
INS380SA models to output internal GPS data. Pins 4 and 6 are designated as the
secondary RS-232 interface pins used by the INU380SA models. The user may opt to set
the output to RS-422 using pin 7. When Pin7 is shorted to ground, the standard RS-232
ports will be available. When Pin 7 is left open, then only the main serial interface will
be available and it will be standard RS-422 , 9600, 19200, 38400, or 57600 baud, 8 data
bits, 1 start bit, 1 stop bit, no parity, and no flow control and will output at a user
configurable output rate. Pins 3 and 4 are used for the RS-422 +Rx and
–
Rx, and pins 5
and 6 are used for the RS-422 +Tx and
–
Tx. These settings allow interaction via a
standard PC serial port. The serial data settings can be configured on a DMU380SA
Series unit with NAV-VIEW. In order to set the serial data interface, select Unit
Configuration, under the Menu Tab.
Serial GPS Interface (INS380SA)
2.5
The internal GPS receiver in INS380SA products outputs data in NMEA-0183 format as
defined by the National Marine Electronics Association (NMEA), Standard For
Interfacing Marine Electronic Devices, Version 2.20, January 1, 1997.
The packets are sent at 9600 Baud, 8 data bits, 1 start bit, 1 stop bit, no parity bit, and no
flow control and are output over the secondary serial interface (RS-232 on pins 4 and 6).
The GPS receiver outputs the following messages as shown in Table 4. (Refer to
Appendix B for the detailed message format)
Table 4.
GPS Output Packet Format
NMEA Record
Description
GGA
Global positioning system fixed data
RMC
Recommended minimum specific GNSS data
VTG
Course over ground and ground speed data
External GPS Aiding (VG380SA and AHRS380SA)
2.6
The VG380SA/AHRS380SA allows the use of an external GPS receiver to be connected
to the secondary serial interface (RS-232 on pins 4 and 6) port. The user is required to
configure the GPS receiver to output the GPS messages that the DMU380SA Series
expects. The table below shows the supported GPS protocols and guidelines for
configuration. Note that the details of the GPS messages can be found in the respective
GPS protocol documents. The user must configure the VG/AHRS380SA to accept
external GPS information using NAV-VIEW as described in Chapter 3. If the
VG/AHRS380SA is parsing valid external GPS data and the GPS receiver has 3D lock,
then the comStatus
noExternalGPS flag will be zero, otherwise it will be one. See
section 9 for a complete description of system status indications.
Since NMEA protocol does not provide vertical velocity, the vertical velocity that the
DMU380SA Series estimates (based upon GPS altitude changes) may not be sufficient
for airborne applications (See Table 5). Therefore, the NMEA protocol is not
recommended for airborne applications.
