Installation guide

LMU Users Guide

V1.0.6 December 10 2009

- 14 - CalAmp Proprietary & Confidential

4.2.5 High Temperature Input

The LMU-1100 and LMU-1200 have a built in high temperature threshold of 60 °C. If the

internal temperature of the LMU is above this value, then the input will be in the High state.

If the LMU’s temperature is below this value, then the input will be in the Low state.

4.2.6 The 1 Bit Bus

The 1-Bit-Bus allows the LMU-4100™ and LMU-2500™ to be connected to a variety of 1-

Wire® Devices. The LMU-4100™ supports the iButton Driver ID products and the LMU-

2500 supports the iButton Driver ID and Temperature Sensor products.

To connect an iButton DS9202 Probe to the LMU you would connect the Black wire to

Ground (Pin 16 on the LMU-2500™and Pin 5 on the LMU-4100) and connect the Grey

wire to the 1-Bit Bus input (Pin 17 on the LMU-2500™ and Pin 7 on the LMU-4100™) as

shown below.

Figure 2 - Sample 1 Bit Bus Wiring

On the LMU-4100™, the 1-Bit Bus interface must be enabled by setting Bit 0 of S-Register

171.

Enable 1-Bit Bus Input/ Disable Output 0:

AT$APP PARAM 1024,51,1,1

Disable 1-Bit Bus Input / Enable Output 0

AT$APP PARAM 1024,51,1,0

On the LMU-2500™, you must select which device the LMU is using (i.e. iButton Driver ID

tag or Temperature Sensor) on the 1-Bit Bus interface using Bit 6 of S-Register 171. The

temperature sensor is enabled when Bit 6 is set and the ID tag is enabled when Bit 6 is

cleared.