Installation guide

LMU Users Guide
V1.0.6 December 10 2009
Copyright ©CalAmp DataCom Inc 2009
- 108 - CalAmp Proprietary & Confidential
For this example, the data will be in the LM Direct format
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14.1.4 LMU Setup – Development
which will be sent to your
production server and, on the peripheral front, we will be using the CalAmp Bluetooth
Adapter using GPS and Dial-Up Networking.
14.1.4.1 Setting up the Inbound Address
Typically the first step in any setup is to program the LMU with the Inbound Address of
your LM Direct server. In this case we are going to assume we have an LM Direct server at a
hosting center using the IP address of 172.90.80.241. We have gone one step further and set
up a URL that will point this customer’s LMU’s to this IP address. The URL is
“HED.HSIInc.com”.
Our first two setup commands therefore are:
AT$APP INBOUND 172.90.80.241:20500
AT$APP PARAM 2319,0,”HED.HSIInc.com”
14.1.4.2 Outputting NMEA data
The Local Application collects its GPS data via NMEA messages. Specifically the application
needs the GGA and RMC messages as a minimum. To enable these messages you would set
bits 0 and 4 of S-Register 128, thus our next setup command is:
ATS128=17
Alternatively we could have done this via Parameter masking using:
AT$APP PARAM 1024,8,1,1
AT$APP PARAM 1024,8,16,16
We also want to make sure the performance of the GPS receiver is going to be as accurate as
possible. For this reason we want to make sure SBAS support is enabled. SBAS support is
controlled by bit 4 of S-139 and would give the command of:
AT$APP PARAM 1024,19,16,16
The last thing we want to look up is the update rate. In this case we are going to be running
multiple applications over an ‘unreliable
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’ connection so we want to minimize the amount
of data being processed. This would push us to use the 1Hz update rate instead of 4Hz. The
update rate is controlled by bit 7 of S-139. The command to set the LMU to 1Hz updates
would be:
AT$APP PARAM 1024,19,128,128
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It’s rare that it’s not.
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It’s common to refer to most wireless links as ‘unreliable’ due to the increased effect over interference
when compared to wired connections.