AMC 1ACOs, Instructions Manual, Page: 24 / 33

AMC-1ACOs One Channel CO Monitor with DSI
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SW2-1 Left VFD Selector for Voltage or Current
Up – Current
Down – Voltage
SW2-1 Right VFD Selector for 0 or Offset (2V/4mA)
Up – 2V/4mA offset
Down – No offset
SW4-1 Left CH 1 Selector External or On Board Electro-
chemical Sensor
Up – On Board Sensor
Down – External
SW4-2 Right CH 1 Selector External Input Resistor 10K or
100R
Up – 100R Input Resistor
Down – 10K Input Resistor
SW5-1 Left CH 2 Input Selector for Voltage or current
N/A
SW5-2 Right CH 1 Input Selector for Voltage or current
Up – CH1 Input Current
Down – CH 1 Input Voltage
TABLE 7: Detailed descriptions of dip switch settings
Service Mode
Default setting is normal, this mode must be selected for regular
operation. Service mode is used by trained technicians to simulate a full
scale gas reading on the available channel(s). Proper precautions must
be taken for resulting alarms.
External or On Board
Electro-chemical
Sensor
Sets the operation of an external or on board sensor for a given channel.
The on board or external operation of each channel is factory set per
order. Please consult Armstrong Monitoring for available configurations.
External Input
Resistor Selector:
10K or 100R
Selects the input resistance required for the specific channel. This
setting is dependant on the selection of an external transmitter and if the
input is voltage or current driven. When a external 4-20mA transmitter is
employed the setting must be set for a 100R input resistance. If an
external transmitter is configured for a voltage output (non 4-20mA
signal) ie. AMC multidrops, the 10K input resistance setting is required.
Input Selector for
Voltage or current
Configures the input required to interpret the signal from the external
transmitter employed. For an on board sensor, a 4-20mA, or current
driven transmitters select current input for the appropriate channel. If an
AMC multidrop or voltage driven transmitter is used, select voltage input
for the appropriate channel. Table 11 indicates the cross reference for
current out when a voltage driven transmitter is used.
VFD Voltage or
Current Selector
Selects the output mode for the VFD signal. Voltage (0-10VDC) or
current (4-20mA). Refer to VFD Offset Selector for setting the minimum
VFD signal output.
VFD Offset Selector
for 0 or (2V/4mA)
Sets an offset, if desired, for a zero reading from the sensor/transmitter
input. In voltage mode the VFD offset is 2V, for current mode the offset
is 4mA. Having an offset is ideal as the offset will help indicated
sensor/transmitter connectivity, i.e. with no connectivity the VFD output
signal will drop to read 0V or 0mA. This unique feature is lost with no
offset as the 0 (V or mA) indicates everything is fine.