Staff Proximity Alarm SM125/7

General Description:
This system has been designed to alert staff in hazardous work environments of the proximity of moving machinery such as forklifts and scissor lift equipment, In addition, it will alert the operators of this equipment when staff approach the vehicle. The system is made up of two components, the SM125 Personal Alert Unit and the SM127 Vehicle Alert Unit.
(The SM125 may be recharged by a dedicated SM126 charging unit, not detailed here.)

The SM125 Personal Alert Unit
The SM125 is a pocket-sized unit equipped with a belt clip. It is designed to be carried by all personnel moving within a designated ‘danger area’ in the proximity of other vehicles and equipment.

It has a 3 position slide switch labelled OFF / ON / SILENT. In the OFF position the unit will not respond to any commands and no power is drawn. In the ON position one of two distinctive beeps will be heard when a vehicle equipped with an SM127 unit is nearby. In the SILENT position, the internal beeper is disabled and the unit will vibrate in either of two distinctive sequences. Whenever the switch position is changed, a brief beep or vibration burst will indicate the present switch position.

When an SM125 Personal Alert Unit is brought within range of an SM127 Vehicle Alert Unit, a one-long, two-short beep sequence will be triggered every 3 seconds.
If the Personal Alert Unit comes within range of more than one vehicle equipped with an alert unit, a different one-long, one-short- one-long beep sequence will be triggered. The Alert LED indicator on top of the unit will flash in synchronisation with the beep sequences.

As different operating environments will have different needs, the proximity alarm range is preset by adjustments during installation. This is typically within 5 and 10 metres The actual range will also vary with the placement of the SM127 unit within the vehicle.

The SM125 also monitors its battery voltage. Should the battery voltage fall below 7.5V the Alert LED indicator on top of the unit will slowly flash (once each second) as a low battery warning indicator. (other flash sequences are suppressed during this time) The low battery warning will not otherwise affect the operation of the unit. The unit will accept either disposable 9V alkaline batteries or rechargeable 9V Nickel/metal hydride batteries.

The unit consumes 9.5ma while in standby which will give approximately 17 hours of continuous use. The unit will fail should the battery voltage falls below 5.5V

The SM125 contains a 1mw UHF transmitter and receiver operating on the LIPD (low interference potential device) Australian Class license frequency of 433 mHz. As such it has the potential to interfere with, or receive interference from other LIPD devices in the same area.

The SM127 Vehicle Alert Unit
The SM127 is a vehicle mounted module designed for use with forklifts, usually within visual range of the operator. It has an internal beeper and two visual indicators. It will operate from either a fixed12VDC or a 24-48VDC supply (as per internal strap settings). It also has an auxiliary relay with NC/NO contacts available to the user to extend proximity alarm warnings and a ‘power on’ indicator lamp

The SM127 broadcasts a weak pulse signal at frequent intervals to trigger a proximity warning on any nearby SM125 Personal Alert Unit, or another SM127 Vehicle Unit. If either module receives this signal, it will automatically generate a return signal to trigger a corresponding proximity alarm on the SM127 Vehicle unit. When one or more Personal Units are detected, the Right-Hand indicator lamp will flash rapidly to indicate a proximity detection event.

When another vehicle fitted with an SM127 unit approaches the first vehicle, this too will be detected, each vehicle unit will perform a double-beep and slowly flash the Left Hand indicator lamp.
Internal option straps can be used to change the interaction between two (or more) vehicles. When Jumper JP4 is removed, the Vehicle Unit Nearby lamp will continue to flash, but audible alarms are suppressed. When Jumper JP3 is removed, both Audible and Visual vehicle alarms are suppressed. (Note that Jumper changes should be performed with the power OFF)

The Auxiliary Relay within the SM127 Unit will operate when any proximity alert event is announced. The contacts from this relay may be used to trip an external audible or visual indicator.

VEHICLE PROXIMITY ALERT SYSTEM
Revision 1.0 January 2004