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RAMPSOAK
Description
Provides an output that tracks a user configured set point versus time profile. The block supports up to 10 separate
profiles with up to 30 user configured ramp and soak segment pairs per profile, for a total of 60 segments (where each
segment is one ramp or one soak)
Each ramp/soak pair is defined by a soak value (i.e., the target value for the ramp segment), a ramp rate and a soak
time. This lets you implement a set point program control function by driving the set point of another regulatory
control function block.
Function
This function is also known as a "set point programmer" because the output follows a sequence of user-programmed
functions, and is typically used as the set point of a PID.
Typically used for automatic temperature cycling in furnaces and ovens. It can also be used for automatic startup of
units and for simple batch-sequence control where the batch sequence is part of a process that is otherwise a
continuous process. This block monitors an input value (typically the PV of the PID), and guarantees that its output
will not deviate from the input by more than some user-specified limits.
This function block may be configured to execute a profile once and stop; repeat continuously the same profile; or
execute the next profile in order after completion of the current profile.
Inputs
Only requires a PV input for the guaranteed ramp option.
Input Ranges
PVEUHI and PVEULO define full range of PV in engineering units. The default range is 0 to 100.
• PVEUHI represents the 100% of full scale value.
and Limits
• PVEULO represents the 0% of full scale value.
Outputs
Block has following initializable outputs:
• OP = Calculated output in percent.
• OPEU = Calculated output in engineering units
Note that the default OP connection pin is exposed on the blocks and the implicit/hidden connection function
automatically makes the appropriate value/status parameter (OPX/OPEUX) connection when required.
Output Ranges
CVEUHI and CVEULO define full range of CV in engineering units. If this block has a secondary, it brings the
and Limits
secondary's input range through the BACKCALC and sets its CV range to that. If it has no secondary, you must specify
CVEUHI and CVEULO range.
• OPHILM and OPLOLM define normal high and low limits for OP as a percent of CV range (user-specified values).
– OP clamps to limits if calculated CV exceeds them, or another block or user program attempts to store OP value
exceeding them; operator may store OP value outside these limits.
• OPEXHILM and OPEXLOLM define extended high and low limits for OP as percent of CV range (user-entered
values).
Prevents operator from storing OP value that exceeds these limits.
(Note that the RAMPSOAK block does not apply a floating bias to the output.)
Guaranteed
If you configure a maximum ramp deviation (MAXRAMPDEV [n]) value for a given profile, the RAMPSOAK block makes
Ramp Rate
sure that the calculated output (CV) value does not deviate from the input (PV) by more than the configured deviation
value
Guaranteed
If you configure the maximum high soak deviation (MAXHISOAKDEV [n]) and/or the maximum low soak deviation
Soak Time
(MAXLOSOAKDEV [n]) value, the RAMPSOAK block makes sure the calculated output (CV) value is at the proper value
before it starts the soak timer.
Event Timers
You can configure up to 16 event flags (EVENTFL [n,e]) to provide Boolean outputs for a specified time during a given
ramp or soak segment in a given profile. This means you can have up to 16 events per profile or a total of 160 events
in 10 profiles.
Parameters on following page
Spare Allen-Bradley Parts
Functional Blocks
Publication 1757-RM810A-EN-P - May 2002
3-47
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