West Control Solutions N8840 - Manual (Page 74)

7.3.6 Bandwidth monitoring
Bandwidth monitoring is valid for all
program segments. An individual
bandwidth can be determined for each
program.
When leaving the bandwidth (b.Lo =
low limit; b.Hi = high limit), the
programmer is stopped (run LED
flashes). The program continues running
when the process value is within the
predefined bandwidth again.
g
With segment type Step and bandwidth monitoring activated, the control
deviation alarm is suppressed, until the process value is in the band again.
g
If band alarm signalling as a relay output is required, a control deviation alarm
with the same limits as the band limits must be configured.
7.3.7 Search run at programmer start
The programmer starts the first segment at the actual process value (search run).
This may change the effective runtime of the first segment.
7.3.8 Behaviour after mains recovery or sensor error
Mains recovery
After power recovery, the last program set-points and the time elapsed so far are
not available any more. Therefore, the programmer is reset in this case. The
controller uses the internal set-points and waits for further control commands (the
run LED blinks).
Sensor error
With a sensor error, the programmer goes to stop condition (the run LED blinks).
After removal of the sensor error, the programmer continues running.
Programmer level
Programmer description 74 8840 profiler
time
process value x
Sp, X
Stop Stop
set-point profile
b.Hi
b.Lo
SP
SP1
Pt (Gradient)
1
SP
SP1
Pt
1