Campbell Scientific PVS4100/4120/4150 Portable Automatic Samplers - Manual (Page 45)

Section 5. Programming
5-5
will begin again. There is no loss of count the sample cycle. Pulse requirements
of the system are detailed in the specifications.
4-20mA INPUT
Where external devices do not themselves generate pulses in any relation to
their process but generate a current signal of 4-20 mA, this input option will
generate internal pulses proportional to the incoming 4-20 mA signal. These
can then be treated the same as the Pulse Input option and accumulated in the
controller to determine when a sample cycle will occur.
EXTERNAL CONTACT
The sampler controller can react to an external dry contact, otherwise known as
a zero-voltage contact, to activate a sample cycle on demand. This will
generally be when external conditions have caused a relay to close, requiring a
sample be taken at that time.
LEVEL CONTROL
The START DELAY function is a special case of the external contact option.
where the contact signal is required to be present for a pre-programmed time.
This enables verification of the signal where fluctuations may occur in the level
which would trigger samples at unwanted times. This is the only case in which
the START DELAY is not a single timed event. The operation of the sampler
after the level signal is verified will be controlled by whatever function is set in
the SAMPLE INITIATION. It will continue until the level drops or the
function is terminated by the controller. If the level drops before the function is
finished, any sample cycle already in progress will be completed and then the
system will shut down until the next verified level control signal.
COMPOSITE
A program option which determines that all the samples that are gathered will
be placed in a single container. The sample program terminates after a specific
number of samples.
MULTI-COMPOSITE
This option is used for discrete sampling applications, to deposit multiple
samples to one container before advancing the distributor mechanism to the
next container. The interval between each sample is controlled by the
SAMPLE INITIATION options. The multi-composite setting is
programmable up to 99 samples per container, for up to 24 containers
depending on the hardware configuration.
CONSECUTIVE
This option is used for discrete sampling applications, to successively deposit
one sample to each of a programmed number of containers on any given
sample initiation. The consecutive setting is programmable up to 99 containers
per sample initiation, although this may be severely limited by hardware
configuration.