Appendix F: PlusBus Installation
ARC Plus Version 3 Instruction Manual
111
Labeling Analog and Status Inputs
The accessory kit supplied with the IIU includes labels to identify the ground pin and supply voltage pin
for each channel. To align and affix the labels:
1.
Start by designating one of the 16-pin connector blocks for metering channels 1-8.
2.
Orient the connector block with the set screws facing toward you and below the wiring
terminals.
3.
Peel off the label identifying ground and supply voltage for channels 1-8 and align the label on
top of the connector block with the ground symbol above the left-most input and the CH 1
designator above the second input from the left. When the label is aligned correctly, the
designator for CH 8 will be positioned above the right-most wiring input and there will be a
small amount of overhang on each side of the label.
4.
Wrap the overhang around the side of the connector.
5.
Next, label a new connector block for metering channels 9-16, followed by the two connector
blocks for status channels. On subsequent IIUs, apply labels for channels 17-32, 33-48, etc. in the
same way.
Note: If you wish, you can apply the label directly on the rear panel of the IIU instead of on the connector
block.
Wiring the Input Channels
Once you have labeled the connector blocks for your input channels, attach wiring for each remote
control channel to the connector block using the connector labels as a guide. Secure the wiring using the
built-in set screws before attaching the connector block to the appropriate rear panel connector.
Metering Input Gain Adjustment
The IIU has 16 pairs of 3-pin headers (one pair for each metering channel, identified on the board by
channel number). These headers allow jumper-selectable gain adjustment for each metering channel. By
default, units ship with the jumpers configured for 1x gain (the IIU uses the voltage inputs as supplied by
the external equipment). This setting is appropriate for typical applications.
If the external equipment supplies a weak voltage sample, resetting the jumpers according to the silk-
screened diagram results in 4x gain (the IIU multiplies the voltage by 4 before scaling the value). Both
jumpers must be moved in unison.
Note: If both jumpers are missing, the associated metering channel will have 4x gain.
Toggling Between Switch Closure and Voltage-Controlled Status Inputs
The jumpers on headers JP1-JP16 on the IIU determine whether the respective status input is driven by
a switch closure or is voltage controlled. By default, units ship with the jumper engaged, enabling switch
closure (the status on condition occurs when the voltage sample is closed to ground). To configure one
or more channels to be voltage controlled, simply remove the jumper.