Chapter 3 SPAN Operation
OEM7 SPAN Installation and Operation User Manual v14
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Figure 30: DMI to PwrPak7 Setup
The DMI connections are A+, A-, B+, B- and GND for quadrature or A+, A- and GND for single channel.
DMI Data Collected on the PwrPak7
Typical DMI hardware generates wheel ticks constantly as the wheel rotates. The PwrPak7 interface is con-
figured to accumulate wheel tick counts at a rate of 1 Hz.
DMI Update Logic
DMI data is available through the
RAWDMI
log. The
RAWDMI
log can be used for applying DMI updates in
post-processing.
The SPAN filter uses sequential
RAWDMI
logs to compute a distance traveled between update intervals (1 Hz).
This information is used to constrain free inertial drift during times of poor GNSS visibility. The filter also contains
a state for modeling the circumference of the wheel as it may change due to hardware changes or environmental
conditions.
Information about how the DMI updates are being used is available in the
INSUPDATESTATUS
log.
Connect the DMI to a PwrPak7
The PwrPak7 DMI inputs are RS-422 differential inputs. Refer to the
PwrPak7 Installation and Operation User
for the required input voltages.
To connect a DMI:
1. Connect the PwrPak7 All I/O Cable, or custom interface cable, to the HD26 COM PORT connector on the
PwrPak7.