Precision Digital PD554 - Manual (Page 24)

This parameter establishes the time units the controller uses for programs and
parameters. This can be set to the format of HH.MM (hours.minutes) or MM.SS
(minutes.seconds). Its default setting is HH.MM.
5.4 Program Group (G.PROG)
Select PROG group from the group display. (Refer to parameter map in section 3.)
This parameter sets the start code to determine what method of SP operation is used when
a program starts. STC (start code) c an be set for SSP (starting set point) or PV (process
variable start). See below for details. The default start code is PV.
PV
PV
PV
STC Operation
SSP START (STC set to SSP)
In Start Set Point mode, the program will begin with at the default set point set in the program (SSP) and ramp
to the set point value for segment 1 (SP1) over the time designated in time segment 1 (TM1).
For a soak segment, the set point for the segment is the same as the set point prior to the soak segment. In this
case, the program will hold the set point at that value for the length of the segment. In the above example, 1.SP1
and 1.SP2 are the same, and the set point is steady for the time indicated in 1.TM2.
PROG SETUP
PTNO
Hold SET/ENT for 3 seconds
Hold SET/ENT for
3 seconds or
no keystroke for 60
seconds
ST
SFT
Operation
Display
SET/ENT
Segment 1 Segment 2
1.TM1 1.TM2
1.SSP
1.SP1
Fig 4: Start Code SSP Start
?
NOTE
In PV mode, the program will immediately start at the point in the program where the set point is equal to the
PV value when the program starts running. In the case where the PV is beyond any set point in the program,
the program will immediately start at beginning of the first soak segment. If no soak segment is present in the
program, it will start at the point closest to the PV.
If the starting point of the program, based on the PV at the start of the program, would occur during a ramp
segment, the p rogram will recalculate the time left in the ramp segment. The rate of set point change in the
ramp will remain the same, and the program will calculate how much time remains in that segment based on
the original rate of change characteristics from the set point of the last segment to the SP of the ramp
segment. Refer to the graphics on the following pages for additional information.
PV Start (STC set to PV)
SP
PD550 Series Nova Programmable Process and Temperature Controller Instruction Manual
24