Installation guide

LMU Users Guide

V1.0.6 December 10 2009

- 54 - CalAmp Proprietary & Confidential

7.8

Both the CDMA and GSM LMUs make use of a back-off algorithm when they encounter

problems connecting to the wireless network (e.g. registration denied, MIP errors, etc…).

Back Off Algorithms

For the GSM LMUs if registration is denied (CREG=3), the modem will be restarted and

the registration wait delay will be increased by the delay schedule. The normal delay is 300

seconds. The back-off algorithm increase this time by 0s on the first failure, 900s for the

second failure, 1800s for the third failure, and 3600s for any subsequent failure. The PDP

session failure back-off requires each of the possible two APNs be attempted with 'n' times

(defined by S-Reg 129) before the back-off kicks in. Once active, the connection dial attempt

is held off by the same schedule as the registration back-off.

For the CDMA LMUs, the back-off algorithm is: 0s on the first failure, 60s on the second

failure, 120s on the third failure, 480s on the fourth failure, and 900s on any subsequent

failure.

The iDEN LMUs do not employ any back-off algorithms.

7.9

The Outbound socket is used when a server other than the Inbound Server needs to talk to

the LMU (e.g. to send configuration changes or unit request messages). This second server is

defined in the second index of the Inbound URL (Parameter 2319, Index 1) and second

index of the Inbound Port (Parameter 769, Index 1).

Working with the Outbound Socket

For example, if your Inbound Server was at LMU.MyCompany.com and the Outbound

server was at Comm.MyCompany.com you would use:

Setup the Inbound Server:

AT$APP PARAM 2319,0,”LMU.MyCompany.com”

AT$APP PARAM 769,0,20500

Setup the Outbound Server:

AT$APP PARAM 2319,1,”Comm.MyCompany.com”

AT$APP PARAM 769,1,20500

The Outbound Socket is only available on the following LMU products:

• MTU-100™

• LMU-900™

• LMU-1100™

• LMU-1200™