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HMR3000 User's Guide
2.8 Configuring the HMR3000 with PC DEMO Software
Following is a list of basic parameters that would be accessed routinely and at installation. Advanced parameters that
control the operation of the magnetometer, heading output, and warning levels are described in the Configuration
Parameters section.
Activate the Tune Parameters button to configure.
Function
Declination
Output Messages
and
Rate
Data Filter
Heading Output
Deviation
2.9 Communication—RS485 Option
The HMR3000 Compass module's RS-485 interface is half duplex, i.e. transmit and receive circuits share the same
physical pair of wires. The HMR3000 must disable its transmitter to allow characters to be received from a host system. If
the unit is operating in the Run mode, i.e. generating repetitive output; then the Run/Stop pin (pin 6) should be forced low
before the host attempts to transmit a command. See details in Description of hardware interrupt section.
2.10 Digital Compass Installation
To get optimum performance when installing the HMR3000, follow the guidelines listed below for your vehicle or platform:
Location—Install the HMR3000 as far as possible from any source generating a magnetic field and far from ferrous metal
objects. Honeywell magnetic sensors used in HMR3000 have a large field range of 2 gauss ( 2 00 µT), compared to 0.65
gauss (65 µT); the maximum of earth's total magnetic field, and therefore would not saturate in most platforms. Calibration
and compensation routines in the compass can effectively compensate for static magnetic fields superimposed on the
earth's field components, which are used for heading calculations. However, compasses can not compensate for the
effects of varying fields produced by dc and ac currents in nearby wires.
Level—The HMR3000 is electronically gimbaled and it is not necessary to mount the compass perfectly level. However,
to get the maximum possible tilt range, the compass should be mounted level (flanges down) when the vehicle or platform
is in normal operation.
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Parameter / Description
Declination Angle
Angle between magnetic north and the
geographic north. Add a declination
angle to magnetic heading to obtain a
true north heading.
HDG, HDT, XDR, HPR, RCD, CCD
NMEA sentence outputs
Rates in sentences per minute
TC1
Time constant for IIR filter
L and S
Smoothing factors for non linear filter
Deviation Angle
The angle between compass forward
direction and that of the platform.
Add deviation to get platform heading
Located Under
Range
General page
Serial Output page
0-255
1=72 ms
0<S<1
L= integer >1
L=0 disable
L<256
General page
0-180 deg
0- 3200 mils
None or All
0-1200
updates/min
0-180 deg
0- 3200 mils
7
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