Transducer Control 5 User Manual (RWT3746IM)
Revision 5, December 2016 - Page 16
Limits
The limits feature allows the user to configure the transducer to control external
processes based on predefined operational parameters. Control is accomplished via
an open collector output on the transducers analog connector. There are numerous
ways this feature could be utilised, some examples include, system shutdown on
overload or triggering a conveyor belt when a nut/bolt has been tightened to the
correct torque.
At present there is a single control line, but the limits feature is very flexible, allowing
the user to control the output polarity, high and low limit threshold, samples before
trigger, and an auto reset function which resets the limit out if the control value falls
back between threshold values.
When Limits is enabled the transducer will monitor the selected control channel,
when the value falls below the low limit (if enabled) or exceeds the high limit (if
enabled), an internal counter is started and is incremented every time a new value is
captured and the condition is met. The counter will be stopped and reset if the control
value falls back between the low and high limits. When the counter exceeds the
“Samples Required Before Trigger” parameter, the limit output will be set to the
active state (level configured using the output polarity). If the auto reset has not been
configured the limit output will remain latched irrespective of the control channel
value. The limit output can only be reset via a system reset or peak switch input
toggle.
If auto reset is enabled the limit function will enter a reset state when the control
channel value falls back between the low and high limits. If the reset timeout is
enabled the limit output will remain latched until the timeout expires, at which point
the fail output will return to the inactive state. The reset stage is cancelled if the
control channel value exceeds the high or low limits during the timeout period, if this
occurs the timeout is disabled and the limit output will remain in an active state. If the
reset timeout is disabled, the limit output will be instantly set to the inactive state
when the control channel value falls back between the low and high limits.
On transducers with firmware version 3 or 4 the limit output is shared with
the Fail Output pin. When limits are enabled the fail output signal is
overridden.
On transducers with firmware version 5 the limit output has been moved to
a dedicated I/O pin, allowing access to both limit and fail signals.
Refer to the Transducer User Manual for more details.
Summary of Contents for RWT420
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