Installation guide

LMU Users Guide

V1.0.6 December 10 2009

- 38 - CalAmp Proprietary & Confidential

5.2.2.3 MDT Mode – Message Termination Length

The Message Termination Length for the Aux port is defined by S-Register 165.

The value of S-165 indicates how many bytes to make the message. The value may range

from 1 to 201 giving a byte range of 4 to 804 bytes. For instance, to set a Message

Termination Length of 200 bytes you would use:

ATS165=50

Setting the value of S-165 to 0 disables the Termination Length feature.

5.2.2.4 MDT Mode – Message Termination Timeout

The Termination Timeout for the Aux Port is controlled by S-Register 168 and ranges from

1 to 255ms. For instance, to set the timeout for 120ms you would use:

ATS168=120

Like the Termination Length, setting this S-Register to 0 will disable the Termination

Timeout feature.

5.2.2.5 MDT Mode – User Message ID

The User Message ID field serves two purposes; first, the LMU will tag any inbound (LMU

to server) User Messages with the defined Message ID. This will appear in the User Message

ID field of the LM Direct packet. The second function is to act as a filter on any outbound

(server to LMU) User Messages. If the outbound User Message does not have the same ID

as the LMU, then the message will not be sent to the serial device. The Message Received

PEG Trigger however, will work regardless of matching User Message ID.

The Aux Port’s Message ID can range from 0 to 255 and is defined in S-Register 166. For

instance, to define a User Message ID of 44, you would use

ATS166=44

This feature is always enabled, so it is very important to co-ordinate this setting with

whoever is responsible for your LM-Direct implementation.

It is also important to note that the LM Direct packet must indicate which port (Host or

Aux) the message should be sent to. Please refer to the LM Direct Reference Guide for

details. In general, it is good practice not to use the same value for the User Message ID on

the Host Port as is used on the Aux Port. At very least this will help the LM Direct server

determine which port was the source of the User Message.

5.2.2.6 MDT Mode – Message Disposition

The Message Disposition defines how the LMU will deal with the User Message. There are

four options: