Installation guide

Access Control by Example Installation with RS-485, AMC and Access PE | en 11
Bosch Security Systems Introductory Guide | 1.0 | 2009.10
The following illustration shows typical locations of electrical components with respect to a
door. Note that the access controller (5) should always be in a secured area to prevent
tampering, preferably in a locked cabinet which has space for the power supply and backup
battery to ensure an uninterruptible power supply.
3.4 Connecting the peripheral components to the wiring
Electrical components must always be connected as per the manufacturer’s instructions.
Nevertheless there are certain basic rules and pitfalls which should be well understood by
every installer of access control devices. Please read the following sections carefully.
3.4.1 Protective diodes
A door opener typically locks or unlocks a door by means of a magnet which is subjected to an
electric current. When this power is switched off a high voltage is induced in the magnetic
coil, which needs to be dissipated to prevent damage to other components. This is generally
done by means of a protective diode.
Door from the outside Same door from the inside
1: Door opener - 2 wires 3: Magnetic contact - 2 wires
2: Reader - 4 wires 4: REX with motion detector - 2 wires
5: Access controller. NOTE: This should not be near the doors themselves, but should
always be located in a secured area (here represented by the cloud).
CAUTION!
If the door opener (or other magnetic component, e.g. a door holding magnet) does not have
an inbuilt protective diode, be sure to connect such a diode electrically in parallel with it. See
illustration below. Section Figure 3.2 Position of the protective diode, page 12. Install
protective diodes wherever excess voltage can be induced by magnetic fields. Suitable diodes
are generally included in the hardware delivery.