Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 244 of 265
38.1.4 Lamp Monitor Load Types
Where LED Signals* are used, the controller must also be configured with the
correct load type for each lamp monitor sensor. This is configured using the IC4
Configurator and/or the KLT handset command.
The load type informs the controller as to the type of signal connected; all signals
monitored by the sensor must be of this type.
Specifying the load type configures various parameters within the lamp monitor. This
includes information such as the nominal current consumed by each signal, which
governs the ‘threshold’ to be used (as referred to in section 38.1.2). It also includes
the expected change in the current given a change in the supply voltage, because
this differs between different types of LED Signal and is very different from the
profile of incandescent lamps.
On an ST900 ELV Controller, all signals are LED types and thus require the load
type to be configured.
A standard ST900 LV Controller cannot monitor LED Signals (except those that
mimic the load of an incandescent lamp*). However, by upgrading to “LED Lamp
Switch” Cards, an ST900 LV Controller can monitor Helios CLS LED Signals (NLM;
with No LMF Module). Refer to the handbook 667/HB/32921/007 for details. This
type of controller is sometimes referred to as an “ST900LED Controller”.
Refer to the handbook 667/SU/32900/000 for a list of the types of LED Signals
supported by the controller.
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* Some LED Signals (e.g. Helios CLS Signal with an LMF module or Helios LED Signal) mimic the
load of an incandescent lamp and thus can be monitored as lamps rather than LED signals.