Chapter 3
Chapter 3 I/O Modules 3-55
External Control (Gate mode)
Besides the GND and counter terminal each channel has a gate terminal to
connect an external gate signal. The gate signal (high or low) can trigger the
counter to start or stop counting. The gate mode can be either low, high or
disabled (low means that counting starts when the gate signal is low and
stops when the gate signal becomes high)
Programmable Alarm Output
The ADAM-4080 module provides a configurable alarm for each counter.
The ADAM-4080D provides high and low alarm functions for counter 0.
When the counter reaches an alarm limit, it will trigger the built-in digital
output for machine ON/OFF control. The alarm limits may be downloaded
into the module's EEPROM by the host computer. The initial count value of
ADAM-4080 module's counter can be configured as any values.
The alarm functions can be enabled or disabled remotely. When the alarm
functions are enabled, digital output channels are used to indicate the alarm
states. For ADAM-4080, digital output channel 0 equals the alarm state of
counter 0, and digital output channel 1 equals the alarm state of counter 1.
For ADAM-4080D, digital output channel 0 equals the low alarm state of
the counter 0 and digital output channel 1 equals the high alarm state of the
counter 0.
Every A/D conversion will be followed by a comparison with the alarm
limits. If the input value exceeds one of these limits, the corresponding
alarm state is set to ON.
There are two alarm mode options for the ADAM-4080D: momentary and
latching. If the alarm is in latchinng mode, the alarm will stay on even when
the input value returns within limits. An alarm in latching mode can be
turned off by issuing a Clear Alarm command from the host computer. A
latching alarm is cleared by the module when the opposite alarm is set. For
example: the alarm is in latching mode and the high alarm is turned ON.
When the module receives a value that is lower than the low alarm limit, it
will clear the high alarm and turn the low alarm ON.
When the alarm is in Momentary mode, the alarm will be turned OFF as
soon as the input value returns to within limits.
The arrangement of coupling high and low alarm states with digital output
lines may be utilized to build ON/OFF controllers that can operate without
host computer involvement.
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