User’s Manual
29
4.2.3. MASTER / SLAVE CONTROL (200 AMP TO 1600 AMP)
Several braking modules can be connected in parallel for current ratings
higher than possible with a single module. This method requires that one
module be in control of all other modules. This module is considered the
Master and the others are slaved to it.
If the output of modules is wired in parallel, severe current imbalances will
damage the units.
Parallel modules do not have to have the same current rating; however, each
module must have a load resistor appropriate for the individual module’s
current rating.
Up to 10 additional modules can be driven from a Master module if all Slave
modules are within close proximity of the Master module.
In this configuration, any module can be selected as the Master module, and
can be changed “on the fly” remotely.
AT NO TIME should more than one Master be selected simultaneously. If
multiple masters are selected, all but one will detect the condition and
cease operation. This fault can only be cleared by powering down the
system and powering back up with only one master module. Ensure that
the logic control will select only one Master at any given time.
4.2.3.1. WIRING FOR MASTER / SLAVE OPERATION
The control signal for parallel systems should be wired in a “daisy chain”
configuration, with all (+) signals connected and (-) signals connected.
Use twisted/shielded pair cable for interconnection. See and Section 3.5
for typical configurations.
Do not exceed 15 feet of total cable length to connect the Master pulse to
the farthest Slave module.
Excessive distance can lead to unacceptable noise in the signal lines, and
can cause false triggering, poor operation, or catastrophic system failure.
4.2.3.2. CONFIGURATION
Master mode is selected by setting the Master Bit in the input word.
All modules have a status output indicating that the module’s bus
regulation and power switching circuitry are functioning properly.
If a Master module faults it will continue to control slave modules as long
as it is enabled and there is no logic voltage fault. The Master module
with the fault will not switch its own power stage. This allows the braking
system to operate at reduced capacity in the event of a Master module
power stage failure.
If a Master module experiences a logic voltage fault, or is disabled no bus
regulation will occur.
For modules selected as Slaves, the unit must have no faults for that
module to switch and regulate the DC bus. The operation of other
modules is not affected.
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