Installation guide

LMU Users Guide

V1.0.6 December 10 2009

- 50 - CalAmp Proprietary & Confidential

The master enable/disable setting is controlled by bit 3 of S-Register 154. Setting this bit will

disable the Connection Monitor, clearing it will enable monitoring. To enable the Monitor

you would use:

AT$APP PARAM 1024,34,8,0

To disable it, you would use:

AT$APP PARAM 1024,34,8,8

When using the LMU to establish a Dial-Up Networking session with a laptop or PDA, it is

best to disable the Connection Monitor.

7.3.4 Querying the modem for network status

The LMU periodically polls the modem for network status to populate the Carrier ID and

RSSI fields of the LM Direct messages. In the case of CDMA and GSM devices, it is

possible to configure how often this occurs. The query interval is controlled by S-Register

153. The value of this register is in seconds. For instance, to program a query every 10s you

would use:

ATS153=10

If the modem fails to respond to 3 consecutive queries, the LMU will reset it.

7.4

This feature only applies to LMU-1000s and is similar to the automatic reset features of the

LMU-4100. The LMU-1000’s firmware is actually hosted within the wireless modem and

thus an automatic reset of the modem is impossible. To attempt to deal with stale data

connections or other possible hang ups, the LMU can automatically refresh its PDP Context

(i.e. the data session).

PDP Context Reset

The LMU will automatically reset the PDP Context of the wireless modem if there has been

no data activity for the length of time indicated by S-Register 172. This timer is always active

and is reset every time there is data activity for the modem, either incoming or outgoing.

The value of S-Register 172 is in minutes. For example to reset the PDP Context after 30

minutes of inactivity, you would use:

ATS172=30

7.5

The LMU has the ability to Prefer, Require or Exclude a specific network based on that

network’s ID and the technology employed by the LMU.

Network selection

If the LMU is set to Prefer a given network, it will first attempt to connect to that network

before establishing a data session. If it cannot find that network, it will register to whatever

network is available.