Mach LED 2
MC/SC
Dr. Mach
Lamps and Engineering
59160001-MCSC
Edition 06
08.05.2013 / Bak page 15/34
4.9. Basic operating mode of the communication on Dr. Mach LED lights
The communication of the Dr. Mach LED lights is realized with a single-wire bus.
The members of the communication bus have star-shaped connections. All the members of the commu-
nication bus need an explicit communication number which is to be set with the first two dip-switches on
the control board. Due to the fact that two dip-switches are reserved for addressing, maximum four inde-
pendent lights can be connected to the communication bus. The communication number of each light is
pre-set by the factory and can be changed during installation on site only by opening the light head. The
communication number is shown by the sticker “Sync address” on each 5-pole light head. Usually at Dr.
Mach the LED 3 lights have the pre-set sync address = 0 and the LED 5 lights have the pre-set sync ad-
dress = 1. Although the sticker is labeled “Sync Address”, it refers not only to the communication between
the light heads, but also to the communication to the wall panel. The light heads of a system must have
different sync addresses, otherwise the communication is not working perfectly. If it is known after placing
the order that a combination LED 3 / LED 3 and another combination LED 5 / LED 5 was ordered, these
combinations will be pre-set with different sync addresses. This way it is ensured that the lights must not
be opened at installation. It means also that in case of deliveries with many lights for many operation the-
atres it must be observed very carefully, which lights are going to be combined.
The communication of the lights with the wall panel works with the same single-wire bus. On the control
board inside the wall panel there is the dip switch 4 which defines that this control board is working as a
wall panel. The dip switch inside the wall panel must be in “ON” position. The control boards inside the
wall panel must have the same sync address as the lights they are assigned for. The same communica-
tion address on the control board inside the light and the control board inside the wall panel makes sure
that the communication with the wall panel is working.
Technical remarks regarding the communication
The communication between the lights and between lights and wall panels is working through one cable.
The voltage on this cable in standby modus is approx. 5-6V.
The communication wire can be found on the control board besides the connections for the power supply.
The wire leads directly to the controller chip. The controller pin is quite sensitive to negative voltages. This
means that if there is a negative voltage bigger than –0,3V on the communication pin, this pin gets dam-
aged and lies on a voltage of approx. 1V.
After a correct installation and during regular operation no negative voltages occur. However, during the
light installation and wiring equalizing currents can appear, which lead to a negative potential on the
communication pin relative to the 0V wire. In this case the pin gets damaged. This is the reason why dur-
ing installation the power supply of the entire system must be completely switched off and there must be
no residual energy in the capacitors (electronic power supply and light head). The electronic power sup-
plies are equipped with quite big-sized capacitors, which have high voltages for several minutes after
switching off the primary voltage. The capacitors must be discharged before the communication lines of
the light and the wall panel are connected.
The reference potential for the communication is the 0V wire of the power supplies. Due to the fact that
each light needs its own power supply, the 0V wires of the power supplies must be connected to each
other in order to create the same reference potential for the communication. Usually the wiring on the
flange is factory-made. However during installation it should be observed that the 0V wires of all the pow-
er supplies that are used for lights with communication, are bridged.
The protective conductor (green-yellow) has no use for the communication. There must not be any con-
nection between the protective conductor and the communication line, because it cannot be ensured that
the protective conductor has a 0V potential all the time. In case the communication line is in contact with
the protective conductor due to an installation error it is possible that the communication does not work
correct. Eventually the function failure is not directly visible and consists of sporadic malfunction or re-
peated pressing of the keys on the keypad in order to control the light.
