Chapter 3
Chapter 3 I/O Modules 3-3
Event counting (Except ADAM-4013)
The event counter is connected to the Digital Input channel and can be
used to keep track of the total amount of external low-speed pulses. Its
accumulated maximal count is 65535. The number 65535 is held, even if the
actual number of events exceeds 65535. The counter can be read or reset to
0 by the host computer.
Since the Event counter’s data is not stored in EEPROM, the event counter
is cleared and set to zero after every reset or power up of the analog input
module.
Alarm signalling (Except ADAM-4013)
Analog input modules include High and Low alarm functions. High and
Low alarm limits may be downloaded into the module’s EEPROM by the
host computer.
The alarm functions can be enabled or disabled remotely. When the alarm
function is enabled, both Digital Output channels are used to indicate the
High and Low alarm state. Digital Output channel 1 (DO1) equals High alarm
state and Digital Output channel 0 (DO0) equals Low alarm state. The High
and Low alarm states can be read at any time by the host computer.
Every A/D conversion will be followed by a comparison with the High and
Low limit. When the input value exceeds one of these limits, the High or
Low alarm state is set to ON.
There are two alarm mode options: Momentary and Latching.
If the alarm is in Latching 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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