2 5
Programming cont.
TRANSMITTER ZERO OFFSETS
TRANSMITTER ZERO OFFSET - MANUAL/ AUTO ZERO FUNCTION
The K1600 is designed to accomodate tank transmitters with either a direct 4-20 ma
output or pneumatic pressure output converted to a 4-20 milliamp signal. The 4-20 milliamp
signal is converted to digital counts by the
A
nalog
to D
igital converter board in the K1600. The
K1600 utilizes a "live" zero which provides an easy means of compensating the inventory
display for transmitter zero shift, both above and below 4.00 ma. When a 4.00 ma signal
from the transmitter is applied to the input termination board, the current
AtoD
count for a
particular channel should read about 50 counts.
Transmitter outputs can shift for a variety of reasons, most notably due temperature
fluctuations. If not adjusted or compensated for, transmitter shift will cause errors (either
high or low) in inventory readings.
The Transmitter Zero Offset represents the
A
nalog
to
D
igital count which corresponds to
the transmitter output (presumably 4.00 ma) when the product level in a tank falls below the
transmitter. The Zero Offset value for a particular tank can be viewed by pressing the
<TIME/ZERO>
button when in the single tank display mode and verified by comparing it to the
actual
AtoD
count currently being converted from the level sensor when the tank is empty .
The value on the left (Offset value) should match the current AtoD value on the right. If they
do not, corrections can be made directly to the Zero Offset at the K1600 without physically
adjusting the tank sensor. This
AtoD
number represents the zero setting of the transmitter
and will be used in determining the net AtoD value required for calculating inventory.
Typically, a transmitter output of 4.00 milliamps should read approximately 50 AtoD counts.
Shifts in P/I transmitter zeros with pneumatic sensors, when used in conjunction with the
KIO-12 or KIO-16 pneumatic input enclosure, are automatically monitored and compensated for by
the K1600 on a preprogrammed time interval and therefore cannot be manually programmed.
