TRANSMITTERS:

Single button keyfobs which can be used in simple two floor systems to call a lift. When the vehicle is fully inside the lift car, either the lift doors close automatically and the lift car transfers to the other level, or a second burst from the keyfob initiates the door closing and transfer Alternatively, the user can press buttons which are mounted on the inside of the lift car side wall and are accessible via the driver’s door window. This technique also allows access to multiple levels.

• Two button keyfobs
which allow two or three functions to be selected (the third function is obtained when both buttons are pressed). Your custom legend is engraved on the front.

Internal Receivers are for use within areas of the car park that are protected from the weather. Types are available for surface mounting, ceiling mounting and flush mounting.

The surface mounting types are housed in Polycarbonate enclosures or in standard BS1363 type double mains plates. The Polycarbonate housings are similar to the ones shown in the "External Receiver" section below. Ceiling mounting types are useful inside lift cars. They are mounted in the centre of the ceiling and activated by signals reflected from either door of the lift car; this allows the vehicle to face either way and still need only one receiver.

Flush mounting types can be built into matching lift furniture housings, eg stainless steel, or can be housed in standard BS1363 type double mains plates. The BS1363 type needs a standard double back box of 25mm depth.

 

EXTERNAL RECEIVERS:

External receivers are for situations exposed to the elements. The external receivers are housed in IP66 Polycarbonate enclosures and are mounted on an assembly which has an adjustable hood and tilts the receiver slightly downwards. The downward tilt is optimised for mounting heights of around 3m. The hood shields the Infra Red sensor from direct sunlight (the sun is a powerful Infra red transmitter and can swamp the receiver with "signals"). The mounting plate is compatible with standard conduit outlet boxes or can be fixed directly to any surface.

LIFT INTERFACES:

The Remote Control System interfaces with the lift system via Lift Interfaces. Generally each receiver will have an interface, although there are situations where two receivers drive one interface on an "either/or" basis. Interfaces can be independently housed or can be housed with the receiver in the lift furniture or in a Polycarbonate housing. Alternatively, they can be supplied for DIN rail mounting. These would typically be mounted with other Lift Control equipment within the Lift Control cabinet.

The electrical connection to the Lift system is via volt-free relay contacts. Each interface will have from one to four change-over relays with gold flashed contacts and RC contact suppression. These can be used in any circuits from "dry" to 240V ac at 8A. Typically the relay contacts would be used to substitute or duplicate the function of push buttons that operate the lift control system. In many situations each receiver has a single function that is determined by it’s location, eg "Call Lift" would be located near the access to a lift car; "Transfer" would be inside the Lift Car. In these cases the Lift Interface needs only a single relay. The interface is powered by 230V/115V ac mains and provides the power for the receiver(s). If the receiver is remote, it connects to the interface via a lightweight low voltage signal cable. This has from three to eight conductors, depending on the system.

The Infra Red signals act in the same way as visible light. The receivers should be in direct line of Sight from the keyfobs for normal operation. Reflected IR signals can be used but the range will reduce depending on the nature of the surface. White or shiny metal surfaces are good reflectors. The use of reflected signals is useful, for example, inside a Lift Car where a ceiling mounted single receiver can be used for vehicles that may be facing either (eg, entering or leaving). The user’s IR signals are reflected from the end doors of the Lift Car. The range requirement in this case is small.

Although resistant to optical interference, it is still best to mount the receivers to minimise direct illumination by tungsten or fluorescent lighting or sunlight.

The external receiver has an adjustable hood which should be set to allow direct line of site for normal keyfob signals but obscure other inputs. Be sure to mount the external receiver in "Portrait" mode with the receiver lens at the top. The internal receivers can be mounted in any orientation.

SECURITY

Some lift Control Systems may also fulfil a security role, eg opening access gates. In this case the system must be highly resistant to interference from extraneous signals. Various features of the system help to meet this requirement

• The receivers respond only to Infra Red signals; they are unaffected by radio signals or interference (eg mobile phones, electrical discharges)
• The signal is pulse coded onto a 500kHz carrier. 500kHz is a "non-standard" frequency, much higher than the normal 38kHz of consumer IR controls. This also makes it less prone to interference from electronic ballasts in fluorescent light fittings.
• The pulse code is a 9 bit* trinary code which has almost 20000 combinations
• The pulses of the code have to occur at the correct intervals +/-5%
• Two correct 9 bit* codes have to be received sequentially.

In addition, for critical and secure applications, the above code conditions have to be fulfilled at the beginning of a transmission and again 0.7s later (the keyfobs transmit for 1.5s).

*NB: For four function receivers, 4 of the bits in the code are allocated to the outputs.

If the receiver is remote from the interface they should be connected in accordance with the supplied Connection Diagram.The cable type is not critical. 7/0.2 stranded is convenient and will give operation up to several 10s of metres. If the run is near to mains cables it would be best to use screened cable.

The receivers and keyfobs can be set to one of 16 possible addresses. The receiver address is set by SIL switch. The keyfob address is set by solder links. Additional combinations are factory settable . The address of the delivered units is stated in the delivery documentation.

T E Electronics manufacture a range of Industrial Control and Security Infra Red products. Please contact us if you can’t find what you are looking for here – we may still be able to offer a solution.

----------------------------