Campbell Scientific PVS4100/4120/4150 Portable Automatic Samplers - Manual (Page 57)

Section 5. Programming
5-17
This option will allow the controller to
determine the SAMPLE INITIATION
based on external pulses. Pulses fed to an
internal accumulator in the controller will be
compared to the setting entered by the
operator and will cause a sample cycle to
start. The accumulator will reset
immediately and counting of pulses will
begin again. There is no loss of count during
the sample cycle. 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 and
accumulated in the controller to determine
when a sample cycle should occur.
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, whose contact will cause a
sample to be taken.
5.4.2 SAMPLE INITIATION using Interval Time
The following sequence of entries are made
on the Touchpad to form a basic operating
parameter for operation of the sampler. This
will determine the time from the start of a
sample cycle to the start of the next sample
cycle. No time is lost during the actual
sample cycle. The ACTIVE SETTINGS are
not being altered.
1. Press the SET key.
2. Press the SAMPLE INITIATION key.