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DE2411U 

MCT/IR-252 WP S

 

Resettable Dual RF & IR Waterproof Transmitter  

User Guide

 

1. INTRODUCTION

The MCT/IR-252 WP S is a miniature, water-proof, resettable, 
microprocessor controlled, personal transmitter designed for use in 
the SpiderAlert signaling network. The transmitter has two buttons, 
used for reporting three different events: Panic (large button), Assist 
(small button) User Defined (by clicking on the two buttons 
simultaneously). The alarm events are supposed to be 
acknowledged and reset by the person who responds to the alarm 
message by holding a magnet close to the pendant. In the case that 
an event is not acknowledged, a No Response message is sent. In 
addition to the above-mentioned events, the transmitter also sends 
low-battery, tracking and supervision messages (when defined in 
DIP switch). The transmitter transmits coded UHF signals and 
pulsed infrared signals simultaneously, thereby allowing the target 
receiver to accurately determine the specific point at which 
transmission took place in multi-storey buildings.  
Besides the regular alert mode, in which an alert message is 
transmitted only once, the transmitter can be set to two additional 
modes – MESSAGE CYCLE and REPEATED MESSAGE 
CYCLING. In the message cycle mode, panic, and assist messages 
are automatically repeated three times, and a no-response 
message follows if the message has not been acknowledged. In the 
cycle repetition mode, a sequence of three alarm messages 
followed by a no-response message (one cycle) is repeated 5 
times, unless the message is acknowledged sooner. The time 
interval between these messages is determined by the DIP 
switches (para. 3.1). When a Panic message is transmitted after an 
Assist message has been initiated, the repeated messages will be 
Panic messages instead of Assist messages. 
When holding an external magnet 
close to the unit, either from 
underneath or on top, near where 
the pushbuttons are positioned 
(fig. 1) the repetitive message 
transmissions will stop and an 
acknowledge message will be 
sent.  

 

Fig. 1 

– Resetting Transmitter

 

Once the button is 
depressed, the LED lights 
and after approximately one 
second the message is 
transmitted.  
It is important not to cover 
the LED during the period of 
time after pressing the 
button. When keyed into 
transmission, the transmitter 
transmits its unique factory  

LARGE

BUTTON

SMALL

BUTTON

BATTERY

COVER

HOLES

FOR

CHAIN

 

Figure 2 –

 MCT/IR-252 WP S

 

programmed, randomly selected 24-bit digital ID code. There are over 
16 million code possibilities, so for all practical purposes no two 
transmitters will have the same ID code. The dual-technology alert 
transmissions made by the MCT/IR-252 WP  S are directed at 
SpiderAlert receivers. These receivers are strategically located all 
over the surveillance area, to pick up alert transmissions and report 
the ID code of the transmitter whose signal was picked up. 

SpiderAlert system

SLC-5UPS

Controller

PC

SR-520

RF+IR

receiver

SpiderBus

MCT/IR-252 WP S

 

Figure 3 – 

Application Configuration

 

Reporting is accomplished via a two-wire bus routed to the 
SpiderAlert Local Control Unit SLC-5, that collects and transfers all 
data to the SpiderAlert main computer automatically displaying the 
holder’s name and exact location. All units are supplied with a 
chain, to be worn around the neck as a pendant transmitter. 

 

2. SPECIFICATIONS

Frequency (MHz):

 315 or 868. 

IR Transmission Range:

 14 m (46 ft) max. with unobstructed line 

of sight (para. 5.2). 

RF Transmission Range:

 30-40m indoors. 

Transmitter ID:

 24-bit digital word, over 16 million combinations, 

pulse width modulation 

Message length:

 36 bit. 

Transmission Duration:

 Limited by timer to approx. 2 seconds. 

Power Supply:

 3V lithium battery Panasonic CR2450 or 

equivalent. 

Current Consumption:

 3

µ

A (standby), 10 mA (transmission). 

Battery Life:

 3 years for typical use. 1 year when using automatic 

tracking. 

Battery Capacity:

 500mAh 

Low Battery Threshold:

 2.5 VDC 

Operating Temperature:

 0° to 50°C (32° to 122°F). 

Dimensions:

 39x60x18mm (1-7/16x2-3/8x5/8 In.). 

Weight: 

40 g (1.4 oz). 

Color:

 Violet Transparent. 

Compliance with Standards: 

FCC ID: GSAWTIR201, CANADA: 

1467 102 270

 

Patents:

 U.S. patent 5,661,471 

 

3. TRANSMITTER MESSAGES

3.1 Internal DIP Switch Functions 

The internal DIP switches functions and their default positions (set 
by the manufacturer) are detailed in table 1. 
To change DIP switch settings, remove the battery as detailed in 
para. 4.1 and set the required DIP switch positions. Position the 
battery in place and secure the battery cover. 
Table 1 - Internal DIP Switch Functions 

SW #  Description 

Default  

Supervision ON/OFF (*) 

OFF 

Cycling ON/OFF (**)  

ON 

Repeat Cycling ON/OFF (***) 

ON 

Retransmission Periods (****) 

OFF 

Retransmission Periods (****) 

OFF 

Automatic Tracking ON/OFF (*****) 

OFF 

*Supervision type 
ON - the supervision messages are transmitted every 60 minutes. 
OFF– No supervision messages are transmitted. 
**Message Cycling 
ON – 3 repetitive PANIC messages are transmitted and then a NO-
RESPONSE message is transmitted. 
OFF – a single PANIC message is transmitted. 
***Repeat Cycling 
ON – The Message Cycle is repeated 5 times.  
OFF – The cycle is not repeated. 
**** Retransmission Periods (Switches 4 & 5): This is the period of 
time between transmission of repeated messages (see DIP switch 
2 and 3) and between the tracking messages (see DIP switch 6) 
when these options are enabled. 
 

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