Campbell Scientific CVS4200 / BVS4300 Stationary Samplers - Manual (Page 46)

CVS4200 / BVS4300 Stationary Samplers
This option will allow the controller to
determine the sampler’s start of operation
based on external pulses. Pulses fed to an
internal accumulator in the controller will be
compared to the setting entered by the
operator. Pulse requirements of the system
are detailed in the specifications.
Where external devices do not themselves
generate pulses in any relation to their
process but generate a current signal of 4-
20mA, this input option will generate
internal pulses proportional to the incoming
4-20mA signal. These can then be treated
the same as the Pulse Input option a
accumulated in the controller to determine
when a sample program should start.
nd
The sampler controller can react to an
external dry contact, otherwise known as a
zero-voltage contact, to activate a sample
program on demand. This will generally be
when external conditions have caused a
relay to close, requiring a sample program
be started at that tim
e.
This option is a special case of the external
contact option. The key difference is that
the contact closure must be present fo
pre-programmed time, thus enabling
verification of the signal. This will
accommodate fluctuations as seen in a level
switch, thereby avoiding triggering of
samples at unwanted times. This is the only
case in which the START DELAY is not a
single timed event. Should the contact open
for the same pre-programmed time, the
sampler will, after completing any sample
cycle already in progress, halt the sampling
initiation and await the next verified signal.
At this time, the sampling program will
resume.
r a
7.6.4.2 START DELAY using Time/Day
The following sequence of entries are made
on the Touchpad to create a future starting
time for the operation of the Sampler. The
ACTIVE SETTINGS are not being altered.
1. Press the SET key.
38