CMU-212 Cabinet Monitor Unit
Operations Manual
Eberle Design Inc.
Page 15
Section 3
INPUT SIGNALS
3.1 FIELD SIGNAL INPUTS
A Green or Yellow signal input will be sensed active when it exceeds 25 Vrms and will not
be sensed active when it is less than 15 Vrms. A Green or Yellow signal between 15 and
25 Vrms may or may not be sensed active. There is programming in the Datakey to disable
the Yellow input for each physical channel.
A Red signal input will be sensed active when it exceeds 70 Vrms and will not be sensed
active when it is less than 50 Vrms. A Red signal between 50 and 70 Vrms may or may not
be sensed active.
3.2 LOAD SWITCH CURRENT
Load current is sensed by the AMU-214 based on total load current to all colors of a
channel. Total load current is an indication that a signal load is present. Lack of adequate
load current indicates no active load (i.e. burned out lamps) or an open field wire condition.
Load current monitoring is used by the Lack of Signal monitoring function (see 2.5) to
detect the loss of signal load while the load switch is in the On state.
A channel will be sensed active when the load current exceeds 105% of the Channel
Current Sense Threshold programmed for that channel in the Datakey. A channel will not
be sensed active when the load current is less than 95% of the Channel Current Sense
Threshold programmed for that channel in the Datakey. A load current value between 95%
and 105% of the Channel Current Sense Threshold may or may not be sensed active. This
provides a hysterisis value of +/- 5% of the Channel Current Sense Threshold.
The Channel Current Sense Threshold should be programmed for each monitored channel
based on the minimum signal load under all worst case conditions.
3.3 PDA CONTROL SIGNAL INPUTS
3.3.1 LOCAL FLASH STATUS
The cabinet should be wired such that operation of the cabinet in AUTO mode will place
AC+ on the LF STATUS pin. Operation of the cabinet in FLASH mode should be open
circuit on this input. This input will be considered active when the input voltage exceeds 89
Vrms. This input will not be considered active when the input voltage is less than 70 Vrms.
Signals between 89 Vrms and 70 Vrms may or may not be considered active. The CMU-
212 will report the state of this input in the Type 189 frame. See section 2.9.
3.3.2 MAIN CONTACTOR (MC) COIL STATUS
The cabinet should be wired such that the MC COIL STATUS input is connected to the
AC+ RAW side of the main contactor signal bus relay coil. An active signal on this input
indicates the Signal Bus should be powering the load switches. This input will be
considered active when the input voltage exceeds 89 Vrms. This input will not be
considered active when the input voltage is less than 70 Vrms. Signals between 89 Vrms
and 70 Vrms may or may not be considered active. The CMU-212 will report the state of
this input in the Type 189 frame.
3.3.3 MAIN CONTACTOR (MC) SECONDARY STATUS
The cabinet should be wired such that the MC SECONDARY STATUS input will be
connected to the output side of the main contactor signal bus relay. An active signal on this
input indicates the Signal Bus is powering the load switches. This input will be considered
active when the input voltage exceeds 89 Vrms. This input will not be considered active
when the input voltage is less than 70 Vrms. Signals between 89 Vrms and 70 Vrms may or
