Contents
Contents
1. Enabled Period 12 Width Do Deadband 3 NOTE Integral Deadband must greater then zero for pulsing to function TUNING Pulsing can be either Enabled or Disabled The Period is the rate of the pulse This number represents the number of passes through the control algorithm task before pulsing The control algorithm task executes every 25 milliseconds The Width determines how long to hold the solenoid valve open Part of this number compensates for allowed noise in the control system Therefore too small a number will not open the valve The Deadbana is the number of counts of error allowed in the system for the pulsing function One count of error is 03 This number is typically 0 3 Contents Data Acquisition The Data Acquisition screen provides a means of saving setpoint and feedback data to a disk file The data can then be viewed using the View functions The sample rate can be any multiple of 100 seconds The user specifies the filename for the data if it already exists a message is displayed warning the user The number of samples can also be specified Or by pressing the start button followed by later pressing the stop button the single button toggles between the two data can be collected under manual control Data Acquisition WARNING START File already exists Old data will be overnarithen Output File daca dat2. 25 0 00 Integral Deadband 0 00 Source External Feedback Minimunn Pulse width Inlet 910 Exhaust 10 The menu item labelled Simple toggles to Advanced reduces the number of parameters displayed and is useful for inexperienced users The following parameters apply to both the Inner Loop and Outer Loop Proportional Term This term multiplies the error Integral Term This term multiplies the integral of the error Derivative Term This term multiplies the derivative of the feedback Integral Minimum This is a lower limit set on the integral the integrator will integrate down to this value Integral Maximum This is an upper limit set on the integral the integrator will integrate up to this value Integral Deadband This causes integration to stop when the error is within this band in percent If this value is set to zero then it has no effect Note By choosing the Format menu item the preceding items can be displayed either as gains or as Bands Reset Rate Gains are simply multiplying factors whereas Bands Reset Rate is the more traditional way of specifying PID values Thus the user should choose one or the other format to enter tuning parameters The next value on the screen ExtFBSource is the source for the external feedback signal The choices are External Feedback and Extra Input 1 Extra Input 1 is only available on units equipped with the additi
3. Signal Toggle v Setpoint 1 25 00 Setpoint 2 75 00 The following screen shows the configuration for Pulse signals Pulsing allows for manually single pulsing the controller s solenoids A pulse width of 100 corresponds to a 25 ms pulse on the inlet solenoid and a pulse width of 100 to a 25 ms pulse on the exhaust solenoid Each time the Pulse button is pressed the controller will output a single pulse Signal Generator gt Setpoint Source Serial Pot Signal type Y Width cnt 50 00 Pulse Note however that the controller will still attempt to perform it s normal PID algorithm even when the signal generator is in pulse mode to overcome this set the Proportional and Integral min max terms to zero to disable PID control If the controller has been set up for profile mode the signal generator appears as follows allowing the user to stop start from beginning of profile or run continue from current location in profile the current profile See Tuning and Profile for more information on configuring profiles Contents Signal Generator ME ES Profile Running Start Profile Stop Profile Run Profile iii Contents Profile The profile screen allows the user to upload generate download save to a file and read from a file profiles which can be run on the controller The ER3000 has the ability to run profiles independen
4. screens which are open This should be done after writing any variable using the Read Write screen Note again that the read write screen is an advanced feature and not normally needed by most users Contents Password The windows tune program provides a means for password protecting each of the screens from unauthorized use To enable password protection choose the password menu item from the main screen Note this menu item only appears if password protection was previously disabled or if the user has previously logged in with a password After choosing the main menu password item the following screen will appear Password Password Disabled Change Password Password required for creer Plot Signal Generator Tuning Failsafe Parameters Pulse Variables Data Acquisition Dacg view le Readwrite Profile To enable the password the first item must be selected to Enable To change the password press the Change Password button The user will then be prompted to enter the old password the software uses the word tescom as the initial password and then enter the new password with verification Next the user can select any of the screens which should be password protected In the screen shown above the Signal Generator Read Write and Profile screens have been selected for password protection The password will not take effect until the next time that the program is run At t
5. Seconds per Sample 0 10 Number of Samples 36000 Delimitter Space File Header Yez sample header comment An optional file header can be written to the start of the file which includes the date and time and a user specified comment Delimiters between data data includes the time with a resolution of 001 seconds the setpoint and the feedback can be specified as spaces tabs or commas Contents Dacq View The View screen provides a means of viewing data which has been previously collected to a file using the Data Acquisition functions VIEW C WORKACY cvis24dacq _ dat oom Header Output 00 05 10 15 20 25 30 35 40 45 5055 6064 Time ec After loading the screen the user must choose File Open to load a data file Up to 10 000 points will be plotted If the file includes a header then choosing the Header menu item will display it in a separate window as shown below HEADER C WORKACY cvis2 dacq dat header Date 12 18 1996 Time 12 50 52 Sample Rate O10 Number of Samples 36000 Comment hiz i sample header comment Once a data file has been loaded the zoom menu item can be chosen to enlarge a region of the plot Alternatively the mouse can be used to choose two corners of a rectangle to zoom clicking with the left mouse button Contents Read Write The Read Write screen allows direct
6. Loop pini Proportional Term 500 Integral Tern Derivative Tem 30 Integral Minimum 0 00 Integral Deadband Minimum Pulse width Inlet 10 Exhaust 10 The first parameter is the control mode When selected the following menu appears Control Mode Cascade Loop Internal Feedback External Feedback Cascade Loop H anual The four options for control mode are as follows Internal Feedback Internal feedback onboard sensor used External Feedback External feedback user supplied sensor used Cascade Loop Both internal and external used Manual Setpoint directly controls the valves lf the controller goes into failsafe mode then FAILSAFE will be displayed for Control Mode and if the controller goes into emergency stop mode possible only with the user interface option then ESTOP will be displayed for Control Mode Note that based on the control mode parameters are shown for the Inner Loop and Outer Loop as appropriate In the following screen the Control Mode is set to Cascade Loop hence both Inner Loop and Outer Loop parameters are displayed compare to screen above which is set up for Internal Feedback Contents Tuning File Format Simple Control Mode Cascade Loop sensor Hange Minimum 10 00 Units 100 00 PSI Inner Loop Outer Loop 1024 Proportional Term 1800 10 Integral Term 500 Derivative Term 0 30 Integral Minimum 2 3 iT
7. Si Integral Minimum Integral 0 Integral Deadband Feedback Minimum Pulse widhi Iriel 10 4 ie Eshaust 10 8 12 Time sec However if we zoom in on the horizontal axis between 1750 and 2000 psi we notice that a small offset remains M Tuning PE Pot lolx Fie Format Simple File Labels eaten Eee i Sensor Range Minimum 0 00 Units Maximum 250000 Outer Loop Proportional Term 1000 Integral Team Integral Minimum o Integral 0 Integral Deadband 00 Source Evtemal Feedback T Minimum Pulse widhi Inet 10 Eshaust 10 Time sec What can be done to eliminate the offset is the addition of integral term The resulting response follows Contents T uning
8. begin three windows should be opened Tuning Advanced Signal Generator Plot Each system has unique requirements and since tuning will always be a compromise between various tradeoffs it is necessary to decide what are the most important parameters for the given application Typical goals include the following Maximize speed of response Minimize peak overshoot Minimize DC offset Minimize settling time In addition the region of operation will affect how the unit is tuned This application will be operating primarily in the 0 to 2500 psi region Thus tuning should be performed over this entire range However the final setup should be tested in intermediate pressure ranges as well to verify maximum performance throughout the system s range In the Tuning Window make sure the Control Mode is set to External Feedback and the sensor Range Minimum and Maximum are 0 and 2500 respectively The ER3000 is shipped with outer loop PID parameters that have been established at the factory to work well with the regulator in that system however in this example we will begin tuning by setting the parameters as follows e Proportional 200 Integral 0 e Derivative 0 Integral Minimum 0 Integral Maximum 0 Note For cascade control it is best to set the Integral Minimum 0 and Integral Maximum 32767 This is because it is necessary to maintain a positive pressure on the dome of the regula
9. Contents Main Screen Windows Plot Screen Signal Generator Profile Tuning Failsafe Miscellaneous Pulse Data Acquisition View Read Write Other Functions Password Communication Handling How to Tune Tuning Procedure Contents Main Screen Normally the first screen displayed upon running the ER3000 software is the main screen Note If communication is not functioning another screen will display first See Communication Handling The main screen consists solely of a menu for accessing various functions ERSO00 Control 250 File Node 78 Aetresh Flot Signal Generator Profile Password Help Tuning Failsafe Miscellaneous Pulse Data Acquisition Dacg View Ready rite The File menu item contains three submenus Save Configuration Change Configuration and Quit Save Configuration will save the tuning parameters from the controller to a file Change Configuration will open a file containing previously saved tuning parameters and download them to the controller Quit is used to exit the program and close any other windows which are open The Node item is used to change the node being communicated to It has two submenus Node Select and List Nodes Node Select allows the user to enter a new node number to communicate with List Nodes produces a list box of all nodes which are connected to the network the user can then select one See Communic
10. access to all of the controller s variables See the ER3000 User Manual for a description of each of the programmable variables Note This function should be used with caution since it can cause inadvertent changes to to controller The user can open up to four read write screens CO rite Read Marable 75 00 Ls anes aoe a ER SOOO 16 BIT DATA SIGNED UN SIGHED 2016 296 B3B Refresh Each screen is set up for either reading or writing via the parameter in the upper left hand corner of the screen The variable number to be read or written can be entered directly or the user can select the desired ID via the list box the box showing ID_SETPOINT above The PSI entry corresponds to the value read reading occurs about once per second or the value to be written This box is visible only for the ID_SETPOINT and ID_FEEDBACK parameters It scales the value read as in RAW ER3000 16 BIT DATA to the Sensor Range and Units specified in the TUNING window Note that the write occurs only once after the user has changed the value Also certain variables are read only and writing to them will have no effect see ER3000 User Manual for details The RAW 16 BIT DATA entries are the SIGNED UNSIGNED and representations of the data read from or written to the controller The Refresh button is used to read up all the parameters from the controller and refresh the
11. ated so that the windows program continues to communicate with the same controller The Feedback Filter is a switch which enables disables filtering of the feedback signal internally in the controller Note that the signal used by the control algorithm is not filtered This is useful for cleaning up noisy transducer signals for display on the plot screen The Solenoid parameter can be set to either NORMAL or REVERSE Reverse corresponds to reversing the action so that instead of opening the inlet solenoid the exhaust solenoid is opened vice versa An example use for this feature would be if an external temperature transducer is used as feedback and the controller is regulating cooling air for temperature control Thus it is necessary to increase the flow in order to reduce the temperature The Serial Number is a factory programmed parameter and should not be changed by the user The Version Number indicates the version of the software in the unit It is not changeable by the user Contents Pulse The pulse mode parameters allow for fine tuning the controller The pulse mode allows for a means of reducing oscillations caused by systems which respond slowly to adjustments made by the controller Pulse mode is only activated within the integral deadband region see Tuning screen Pulsing continues until within the pulse deadband see value below Pulse mode has no effect on the normal control algorithm i Pulse
12. ation Handling for more information Note that the node number with which the program is currently communicating is shown in the Main Screen s title bar This corresponds to the data in all windows The Window item is used to open various other screens See specific sections for each item Plot Signal Generator Profile Tuning Failsafe Miscellaneous Pulse Data Acquisition Dacq View Read Write The Refresh item is used to read up all the parameters from the controller and refresh the screens which are open It is usually not necessary to do this unless parameters may have changed locally The Password item will not be visible if the user does not have password authorization The Help item is used for accessing this online help system Contents Context Sensitive Help This help system is context sensitive If the right mouse button is clicked on any open screen the help system will be called for the appropriate topic Contents Plot Screen The plot sceen is used to graphically display in real time the current setpoint and feedback from the selected controller These values are updated every 100 milliseconds Plot OL gt File Asis Labels PlotStart Pressure p i Time sec The main menu items File Labels PlotStop Time Minimum Wertical Wertical Full Scale Vertical The File item has two subitems Print to print a hardcopy of th
13. e current plot with tuning parameters and Quit to close the plot screen The Axis item is used to set up the ranges for the horizontal and vertical axes Time corresponds to the time along the horizontal axis Selecting Minimum Vertical Maximum Vertical allows for inputing the Minimum and Maximum ranges for the vertical axis Also Full Scale resets the vertical axis to the full range of the controller An alternate method of setting the vertical axis is via the mouse cursor Left clicking at two points on the plot corresponding to the desired min and max of the plot will cause the vertical axis to be rescaled Double left clicking in any area of the plot will cause the vertical axis to be reset to full scale Double left clicking a second time causes the plot to zoom out further The Labels menu item causes the border and labels around the plot to be removed The PlotStop menu item toggles to PlotStart stops and starts the plot Contents Signal Generator The signal generator provides a means for creating a setpoint from the computer and downloading it periodically every 100 ms to the controller Typically this screen will appear as follows Signal Generator i ES Setpoint Source SerialPort Signal Type Square Pernod sec 200 Setpoint 1 25 00 Setpoint 2 75 00 Stop The setpoint source gives the user the ability to determine where the setpoint comes from The four op
14. hat point the user will be presented with the following screen cu Password lf the correct password is entered then the program will the same as if password protection was not enabled Otherwise the following message will appear Contents Password Failed PASSWORD FAILED Try Selecting Yes will allow the user to attempt to enter the password again Otherwise if is selected then the program will be run with the selected screens disabled For example with the selections shown in the screen at the beginning of this help topic the main menu will appear as follows 3000 Control 250 Node 07 Flot Signal Generator Profile Help Tuning Miscellaneous Data Acquisition Dacg View Read rite Notice that the Signal Generator Profile and Read Write menu items appear in grey This means that these menu items cannot be selected Contents Communication Handling If the program is unable to communicate with a controller the following window will appear Comm Error Search Network Prograrn Communication COM Simulate This window will appear if the controller is not properly wired to the computer or if the wrong node number has been selected the user believes that the node number is in error and knows the correct node number then he she can select Change Node and manual
15. ity to shut the controller down if an out of range condition occurs Any combination of the following five parameters can be checked Analog Setpoint range 12 12 to 111 97 Internal Sensor range 12 12 to 111 97 External Sensor range 12 12 to 111 97 Inner Error range 124 12 to 124 09 Outer Error range 124 12 to 124 09 When the minimum value is set to the minimum value above and the maximum value is set to the maximum value above then the failsafe checking is disabled Failsafe Parameters Minimum Analog Setpoint DISABLED DISABLED Internal Sensor DISABLED DISABLED External Sensor DISABLED DISABLED Inner Error DISABLED DISABLED Outer Error DISABLED DISABLED Failsafe Condition Inlet Closed Exhaust Open Disable All When any value is selected via a mouse click the following dialog box is displayed The Out of Range message is displayed if a value entered is not allowed Selecting the Disable button will set the value to it s extreme and thus disable failsafe checking for the corresponding limit Contents Failsafe Value Input new falzate value or press DISABLE DISABLE Data float Min Value 1212 Value 111 9 Default Value 0 00 The final item on the failsafe screen Failsafe Condition allows selecting one of the following conditions to be established should the failsafe condi
16. l Constant i 0z Outer Integral Maximum H 023 0uter Integral Sum 025 Proportional Constant 028 Inner Integral Constant H 029 Inner Integral H 030 Inner Integral Sum OSS Inner Proportional Constant H 037 039 040 H 042 Node Address 043 Setpoint Flag O46 Solenoid Direction H O47 Minimum Inlet O46 Minirourn Exhaust 049 Outer Integral Minimum O50 1 Integral 052 Serial Number H 054 Minimum 40 Setpoint 055 Masimum AD Setpoint 056 Compensated Internal Sensor H 057 Mas Compensated Internal Sensor 059 Compensated External Sensor 059 Max Compensated External Sensor H Min Inner Actual Error Inner Actual Error 2 Min Outer Actual Error H 063 Outer Actual Error 4 PM Failsafe Integral Deadband H 06r Outer Integral Qeadband O68 Feedback Filter 070 Frofile State OF ESTOP Flag 0ra Pulse OF 6 DAC US Range Minimum Inlet O03 Inner Cenvative Coefficient Cancel Contents Tuning The tuning screen contains the main parameters which affect the controller s performance see the Tuning Procedure section for more detail on the tuning process iw Tuning Es File Format Simple Control Mode Internal Feedback sensor Range Minin 0 00 Units Maximum 100 00 p i Inner
17. ly enter a new node number If it is believed that the node number is in error but the user does not know the node number of the controller Search Network can be selected and the software will search for the appropriate node number If it is believed that the communication port is in error the user can select the alternate communication port The program will then exit and it is necessary to restart the program for the new port to take effect Note The port number is stored a file called tescom ini in the windows directory r Quit Program should be selected if all else fails and the user wishes to exit the program The Simulate button can be used to run the software in simulation mode i e without actually communicating with a controller Contents Tuning Procedure This section will cover an example tuning procedure To begin it should be realized that the tuning of PID controllers is learned with experience However the following basic concepts should allow the inexperienced user to tune their loops sufficiently well for the majority of applications There are some features of the ER3000 which are unique compared to other PID controllers and allow the system to be optimized In particular the use of four different modes of operation the setting of minimum values for inlet and exhaust valves deadband adjust and the setting of maximum and minimum values for the integral sum allow for greater flexibility To
18. n example sequence of tuning steps First a very undertuned response is shown note size of proportional term Contents Tuning Elle Format Simple Contol Mode Extemal Feedback Sensor Renge Minimum 000 Units 2500 00 Outer Loop a Proportional Tem 200 gp 1900 integral Perm 0 az TET si 1250 Detivalive Tem o E 100 Integral Mirim 0 0 Integral Deadbsrd 10 am EFBSouce External Feedback 250 Minimum Pulse Width Inlet 10 0 Exhaust 10 Next the proportional term is increased however overshoot ringing results Tuning Mee File Format Simple Fie Label PlotStarl Mode ExternalFeedback w 2500 Range Minimum O00 Maximum 250000 Psi ante eae Outer Loop 7750 D _ Integral ern fats 1250 Cheriw atine 0 E 1000 Integral 0 Integral 0 750 Integral Deadband 0 00 5 ExtemalFeedback _ 250 Minimum Pulse Width Irist 10 0 Exhaust 10 12 Time Now some Derivative is introduced Note the decrease overshoot Contents M Tunings __ File Foma Simple File Avs Labels _ 0 foe Sensor Range Minimum 0 00 Units Maximum 2500 00 Outer Loop Proportional Term 1000 Integral Term o Tem
19. onal digital analog inputs The next two values on the screen Minimum Pulse Width for the inlet and exhaust solenoids are the minimum values which are written to the pulse width modulators They can have a value between zero and 50 50 corresponds to a duty cycle of 20 Essentially these values are used to define the deadband of the output and prevent noise or small fluctuations in the controlled pressure from causing the valves from opening Small values can be used to keep the valves from constantly sputtering and large values to prevent the Contents output pressure from varying much before taking action The following parameters pertain to the Sensor Minimum Range The value corresponding to the minimum for the sensor In the case of an external 4 to 20 mA transducer this is the value which corresponds to 4 mA Maximum Range The value corresponding to the maximum for the sensor In the case of an external 4 to 20 mA transducer this is the value which corresponds to 20 mA Units Up to four characters which the user wishes to use to refer to the reading This string is applied to the plot screen and to the optional user interface Note If the user wanted to set up a system in internal feedback mode to display bar instead of PSI he she would set units BAR minimum range 0 maximum range 6 8947 since 100 psi 6 8947 bar Contents Failsafe Failsafe checking is not usually used however it provides the abil
20. op Chanae WV anshle An End segment is used to end the profile A Ramp segment creates a ramp starting at the current setpoint and ramping to a desired setpoint in a specified time period A Step segment changes the setpoint immediately to a desired setpoint A Dwell holds the current setpoint for a specified period of time A Digital Output is available on the optional user interface 13000 and on units equipped with the digital output electronics Specifying output 1 or 2 selects a digital output on the UI3000 and output 3 or 4 selects a digital output on the ER3000 If available the specified output is set to the specified state A Digital Input is available on the optional user interface 13000 and on units equipped with digital analog electronics Specifying input 1 or 2 selects a digital input on the 113000 and input 3 selects a digital input on the ER3000 If available the profile is halted until the specified input is set to the specified state A Loop causes the profile to loop to a specified profile step a specified number of times if the number is specified as zero then the loop will continue indefinitely A Change Variable allows the user to set an embedded variable to a specified value Some of the variables are shown the following diagram See the ER3000 user manual for the significance of each variable Contents 009 Control O16 Outer Dernvatrve Coefficient 021 Outer Integra
21. output Once the optimal proportional and derivative terms are found the integral term should be adjusted The integral term has the effect of eliminating DC offsets however too much integral will lead to instability overshoot and ringing Again the effect is logarithmic so values such as 10 20 50 100 200 500 1000 can be tried until an optimal value is obtained At this point it should be noted that the ER3000 provides a unique integral limiting feature Minimum Outer Integral and Maximum Outer Integral This allows for using large integral terms without creating excessive overshoot It should be realized that the integral sum is what holds the valves open even when there 1 zero error For closed ended systems the minimum and maximum integrals can be very small However for systems requiring flow it is necessary to keep these values higher To determine how small they can be made remember smaller is better as long as proper flow is maintained the setpoint should be set to the maximum level and the minimum and maximum reduced until flow is no longer maintained then slightly increase these values Often for closed ended systems a value of one or two 1 sufficient After performing the steps mentioned above tuning can often be improved by iterating between the various parameters Although performing basic tuning can be simple learning to fully optimize the tuning requires experience so experiment The following is a
22. tion exist Failsafe Condition Inlet Closed 7 Exhaust Open Inlet Open 2 Exhaust Closed Inlet Closed Exhaust Open Inlet Open Exhaust Open Normally Inlet Closed Exhaust Open should be selected so that the controller vents to atmosphere if a failsafe limit is exceeded The Disable All button can be used to completely shut off the failsafe feature most users will not need to use this feature Contents Miscellaneous The miscellaneous screen contains a collection of parameters which don t fall into the category of any other screen Miscellaneous Calibration ero 2 Number 260 Feedback Filter Solenoid NORMAL Seral Number 4170 B20 Version Number The calibration parameters allow for fine adjustment of the controller From the factory the span is set to 100 and the zero to 0 However the user may find it useful to adjust these parameters to compensate for external transducers for example overstressed transducers which need recalibration Node Number can be input to change the node number of the unit being communicated with Note that this is different from changing node from the main screen When changing node from the main screen the program merely attempts to communicate with a different controller When changing node from the Miscellaneous screen the node number of the current controller is reprogrammed the main screen node is also upd
23. tions are Analog Input Serial Port Frotile User Interface Analog Input The setpoint is to be obtained from the controller s analog input 4 to 20 mA or 1 to 5 V analog signal Serial Port The setpoint is to be sent via the serial port RS485 to the controller Profile The setpoint is to be generated internally by the controller using the previously defined profile User Interface The computer should not send setpoints to the controller since they will be generated locally i e using the optional user interface There are five different signal types available Toggle Square Sine Triangle and Pulse If Square Sine or triangle are chosen then the screen appears as above and the user can enter the period of the wave and Setpoint 1 and Setpoint 2 the peak values for the wave In addition the Run stop button allows for stopping the waveform at the current value Signal Type Square Y Triangle Pulse Toggle is chosen as the wave type then the screen will appear as follows In this case no period parameter is available and the switch becomes Setpoint1 Setpoint2 for toggling between the two setpoints Note that if the Signal Generator screen is opened in toggle Contents mode or switched to toggle mode then setpoint 1 will be set to the current setpoint read up from the controller unless the current setpoint happens to match setpoint 2 Signal Generator 8 Eg Setpoint Source
24. tly of the computer although a computer can be used to generate profile sequences and command the controller to stop or start the running of a profile IMPORTANT THE PROFILE CREATED IS ONLY PRESENT ON THE COMPUTER UNTIL DOWNLOAD IS SELECTED ONLY THEN IS THE PROFILE IN THE CONTROLLER AND CAN BE RUN A typical profile screen follows CH Profile PRINT UPLOAD DOWNLOAD OPEN QUIT Modify Delete 1 5 to 90 00 psi 2 DWELL for 1 0 sec H 3 RAMP to 20 00 pst 1 1 sec 4 LOOF to step no 1 always The PRINT outputs the profile to a printer UPLOAD reads the profile from the controller and displays it on the screen upload also takes place automatically when the window is opened DOWNLOAD writes the newly created or modified profile into the controller OPEN reads a profile from a file SAVE writes a profile to a file QUIT closes the profile window By highlighting a profile step using the up down arrows or the mouse and then selecting insert modify delete the user can create a custom profile Note double left clicking on a profile item also can be used for modifying an item Choosing insert or modify the user is presented with a screen for creating a profile step Segment Selector The types of segments include the following Contents Ramp Shep Dwell Digital Output 413000 1 8 amp 2 ER 3000 38 4 Digital Input UIS000 18 amp 2 ER S000 3 Lo
25. tor to maintain output pressure from the system In the Signal Generator set Setpoint 1 amp Setpoint 2 to 625 and 1875 which is 25 and 75 Make sure that the plot screen is set up to show the entire tuning range For example with the above setpoints the display should be set up for 0 to 2500 Since tuning is generally done using step changes set up Wave for option TOGGLE Now click the Setpoint 1 Setpoint 2 in the Signal Generator to toggle between the two setpoints Contents With the proportional term set to 200 the response will be relatively slow The first step in tuning is to see how far the proportional term can be increased In general increasing the proportional term will decrease the response time i e make the response wave more square however a point will be reached at which the effect becomes detrimental That is too much proportional term will result in overshoot and possibly ringing of the response Also it should be noted that the effect of the tuning parameters PID tend to be logarithmic Thus a possible sequence of values to try for the proportional term might be 200 400 800 1600 until ringing and or overshoot occurs and then narrow down to an optimal value one which gives just a slight amount of overshoot and ringing Next the derivative term should be increased so as to reduce the overshoot and ringing in the system However too much derivative term may result in a noisy
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