Debugging a process control loop
8
At a Glance
Aim of this chapter
What's in this
Chapter?
This chapter describes the process control loop debugging screens as well as the associated operational processes.
This Chapter contains the following Maps:
Topic
Description of the debugging screen
Modifying the parameters of each loop
Functional modification of each loop
Debugging the setpoint programmer
Data storage
Page
204
206
207
208
210
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Debugging
Description of the debugging screen
At a Glance
Illustration l l l l l l
In online mode, the process control debugging screens are used to: display and animate the loop schema, display the process alarms and channel faults, modify the adjustment parameters of each function, simulate input interface values, add, delete, and replace calculation functions, modify configuration parameters of each PID reverse/forward mode type function, l modify loop controller operation modes.
This diagram shows a process control loop debugging screen.
PMX 57102 [RACK 0 POSITION 0 ]
Mise au point
Désignation : PROCESSEUR PMX P 57102
Configuration du DOP
Symbole :
Régulateur :
Régulateur4 - LOOP0
Fonction :
Boucle process
Alarmes
DL DH LL L H HH
DIAG...
DIAG...
WARNING
LOOP 0
Boucle
Paramètres boucle
Mesure
Consigne
Correcteur
Feed Forward
Sortie 1
Standard
Simple
Chaud/Froid
Oui
Analogique
Echelle de la boucle
Basse : 0.0
Haute : 100.0
PV
5000 44.845
SP1
63.0
R
45.0
L
FF
3547 LL 35.47
Fonctions
Format
Filtrage
Générateur Fct
Alarmes
Simulation
Paramètres
Constante de temps (s)
Gain
Sortie
10.0
1.0
4484.536
I
P
D
28.585
0.0
OUT 1
2858
0
OUT 2
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Description
Debugging
This table describes the main fields of the debugging screen.
Address Description
Alarms
Loop 0
If the alarm functions have been configured, all the loop-associated alarms are displayed.
l l the DIAG LED groups together the serious errors, the WARNING LED displays warning messages pertaining to the process control loop function.
When the LEDs are on, a window displays error diagnostics messages.
A %MWxy.i:Xj word bit is linked to each diagnostic. These bits are detailed in the Fault and diagnostics language objects parts of the chapter describing all the process control language objects (See Process control language
objects, p. 283 ).
Only the configured functions are shown in this tab. Their associated parameter values are animated. They can be modified in online mode.
Block schema
The schema shows the intermediary calculation values (corrector input measurement, for example).
Auto/Manu and Remote/Local changes are made by clicking the mouse once.
The associated command values or setpoint values are entered directly in the entry fields.
The grayed out entry fields are not active.
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Debugging
Modifying the parameters of each loop
Principles The adjustment parameters can be modified in online and offline mode from PL7 software: l l l l l l task screens, data editor, runtime screens, variable tables,
UNITE server,
...
Modifications do not require global reconfiguration and the save mechanism (initial parameters, current parameters) is applied to the parameters of each process control loop (See
Data storage, p. 210).
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Debugging
Functional modification of each loop
At a Glance
Principles
Functions can be added to or deleted from the process control loops in online mode .
The PLC can be in RUN mode during modifications to process control loop functions.
DANGER
For safety reasons, modifying these functions and some configuration parameters such as extrapolating the generator function from the function, and limiter lopping, etc. require channel reconfiguration.
Failure to observe this precaution will result in death or serious injury.
After the modifications have been made, the loop starts in a determined state: l If modifications are made at Measurement, Setpoint, and Feed forward branch level, the loop performs a warm start.
l If modifications are made at corrector or output level, the loop restarts using the initial operating modes which were defined during configuration.
Note: addition or modification of I/O addresses or memory words in online mode is prohibited. Modifying some branches, and replacing a simple setpoint with a ratio setpoint is also prohibited.
Note: the totalizer function can not be added in online mode. Its output is a %MF address.
It is not necessary to switch to configuration mode to modify the initial adjustment parameter values Kp, Ti, and Td.
Operating mode : l In debugging mode, all modification of the adjustment parameters from the task screen updates the current and initial values of these parameters.
l For the 3 simple loops configuration parameter modification is not taken into account (for example, adding a function).
loop controller alone, an initial value modification without
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Debugging
Debugging the setpoint programmer
At a Glance Setpoint programmers have their own debugging screen. They have all the reconfiguration and data saving services in online mode.
Note: any reconfiguration in online mode causes the setpoint programmer to stop operating.
Illustration This diagram shows an example of the setpoint programmer in Debugging mode.
PMX 57352 [RACK 0 POSITION 0]
Debug
Designation: PROCESSOR PMX P 57352
DOP configuration
DIAG...
Symbol:
Loop Controller: Function:
Loop controller 5 - SPP_1 Setpoint programmer
Name: SPP_1 0 1 2
Task:
3
MAST
4 5
Segmentation:
8-8-8-8-8-8
6 7
DIAG...
WARNING
PROFIL_1 PROFIL_2 PROFIL_3
Segments Execution
1
2
3
4
Guaranteed Dwell Time at threshold 5.0
Segment x
Ramp
Stage
Ramp
Stage
50.0
50.0
80.0
80.0
SP x
40.0
20.0
40.0
40.0
VAL x
PROFIL_4 PROFIL_5 PROFIL_6
Number of segments:
Unit
Second
Second
Second
Second on Deviation on input
8 on 8
Pq S0 S1 S2 S3 S4 S5 S6 S7
Process value
Setpoint 13.47494
80.0
Current
Profile 1
Total time elapsed
Segment
10.78006
1 No repetition 1
Time elapsed in current segment 10.78006
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Operating principle
Debugging l l l l
Profile execution is displayed dynamically. The information provided is as follows: the segment number in progress (SEG_OUT), the iteration number in progress (CUR_ITER), the execution time of the segment in progress (TIME_SEG), the total time (TIME_TOTAL).
l l l
Notes on the operation:
The TIME_SEG and TIME_TOTAL times change even if the profile is frozen.
The state of monitoring outputs is directly displayed in the channel zone.
Each profile can be controlled directly from the command button located in the tab.
l When the profile is frozen, the %MFxy.i.20 setpoint values and control outputs,
%MWxy.I.3:X0 to X7, are not updated during use of NEXT and BACK commands.
They are refreshed once the profile has been unfrozen.
l Neither the target setpoint value to be reached (SPi) nor the length of the segment in progress can be modified.
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Debugging
Data storage
At a Glance
Saving adjustment parameters
Backup application l l
Two data save solutions are provided: saving adjustment parameters, the backup application.
l l l l
All modifications of the adjustment parameters from the PL7 process control screens update the current and initial values.
Modifying an adjustment parameter from the application or from an animation table affects the current value but does not modify the initial value. The
SAVE_PARAM explicit instruction must be used to save this new value.
A modification from the XBT-F runtime screens affects the current value but does not modify the initial value. An explicit save command, which is available in these screens, is used for updating.
On cold restart (%S0) and application loading, the current parameters are replaced by the initial parameters.
Premium PLCs provide the option of saving the application (program and data memory) on a Backup card. The content of this card can reload the RAM memory.
Note: A backup card cannot be used if the Premium PLC is already using a
PCMCIA card.
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