Specifications

Digital I/O Functions 6-10
The benefit of using SP command is that only one command is necessary
to change the setpoint value. The hysteresis is stored in the HI and LO
alarm registers and does not have to be changed when a new setpoint is
used.
The SP command makes it particularly easy to construct a controller
whose setpoint is a time varying function downloaded from a host com-
puter. The SP command can also be used without control functions
whenever a deviation output is desired.
The setpoint value may be read back by using the Read Zero (RZ)
command. The RZ simply reads back the contents of the output offset
register. The RZ command will always read back the setpoint value with
the sign changed.
The setpoint value is stored in the same register as the output offset trim
(see TZ command). In cases where the output offset register is used to
hold a calibration trim value, the SP command will erase the trim. In most
cases, an offset calibration trim is not necessary and the trim value would
read back as +00000.00 using the Read Zero (RZ) command. If the trim is
non-zero, it must be read and stored by the host before the SP command
is executed. To download setpoint values the host must then subtract the
trim value from the desired setpoint to derive the proper data for the SP
command. To restore the trim, use the SP command to download the
negative of the trim that was previously read back with the RZ command.