Creating and Running Custom Algorithms
129
Writing the
Algorithm
The most convenient method of creating your custom algorithm is to use
your text editor or word processor to input the source code. The following
algorithm source code is on the examples disc in a file called "mxplusb".
/* Example algorithm that calculates 4 Mx+B values upon
* signal that sync == 1. M and B terms set by application
* program.
*/
static float M, B, x, sync;
if ( First_loop ) sync = 0;
if ( sync == 1 ) {
writecvt( M*x+B, 10 );
writecvt(-(M*x+B), 11 );
writecvt( (M*x+B)/2,12 );
writecvt( 2*(M*x+B),13 );
sync = 2;
}
Running the
Algorithm
A C-SCPI example program "file_alg.cs" shows how to retrieve the
algorithm source file "mxplusb" and use it to define and execute an
algorithm. When you have compiled "file_alg.cs", type file_alg mxplusb to
run the example and load the algorithm.
Modifying a Standard PID Algorithm
While the standard PID algorithms can provide excellent general closed
loop process control, there will be times when your process has specialized
requirements that are not addressed by the default form of the HP E1415’s
PID algorithms. In this section we show you how to copy and modify a
standard PID algorithm. Both of the HP E1415’s standard PID algorithms
PIDA and PIDB are also available as source files supplied with your
HP E1415. Also included is a source file for a PIDC algorithm. PIDC has
more features than PIDB but is not pre-defined in the HP E1415’s driver like
PIDA and PIDB. It is only available as a source file.
PIDA with digital
On-Off Control
The HP E1415’s PID algorithms are written to supply control outputs
through analog output SCPs. While it would not be an error to specify a
digital channel as the PID control output, the PID algorithm as written would
not operate the digital channel as you would desire.
The value you write to a digital output bit is evaluated as if it were a boolean
value. That is, if the value represents a boolean true, the digital output is set
to a binary 1. If the value represents a boolean false, the digital output is set
to a binary 0. The HP E1415’s Algorithm Language (like ’C’) specifies that
a value of 0 is a boolean false (0), any other value is considered true (1).
With that in mind we’ll analyze the operation of a standard PIDA with a
digital output as its control output.
How the Standard PIDA
Operates
A PID is to control a bath temperature at 140 degrees Fahrenheit. With the
Setpoint at 140 and the process variable (PV) reading 130, the value sent to
the output is a positive value which drives the digital output to 1 (heater on).
Содержание VXI 75000 C Series
Страница 2: ......
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Страница 30: ...30 Getting Started Chapter 1 Notes ...
Страница 32: ...32 Field Wiring Chapter 2 Figure 2 1 Channel Numbers at SCP Positions ...
Страница 44: ...44 Field Wiring Chapter 2 Figure 2 11 HP E1415 Terminal Module ...
Страница 54: ...54 Field Wiring Chapter 2 Notes ...
Страница 61: ...Programming the HP E1415 for PID Control 61 Chapter 3 Programming Overview Diagram ...
Страница 124: ...124 Creating and Running Custom Algorithms Chapter 4 Figure 4 2 Algorithm Operating Sequence Diagram ...
Страница 136: ...136 Creating and Running Custom Algorithms Chapter 4 Notes ...
Страница 152: ...152 Algorithm Language Reference Chapter 5 Notes ...
Страница 304: ...304 HP E1415 Command Reference Chapter 6 Command Quick Reference Notes ...
Страница 308: ...308 Specifications Appendix A Thermocouple Type E 200 800C SCPs HP E1501 02 03 ...
Страница 309: ...Specifications 309 Appendix A Thermocouple Type E 200 800C SCPs HP E1508 09 ...
Страница 310: ...310 Specifications Appendix A Thermocouple Type E 0 800C SCPs HP E1501 02 03 ...
Страница 311: ...Specifications 311 Appendix A Thermocouple Type E 0 800C SCPs HP E1509 09 ...
Страница 312: ...312 Specifications Appendix A Thermocouple Type E Extended SCPs HP E1501 02 03 ...
Страница 313: ...Specifications 313 Appendix A Thermocouple Type E Extended SCPs HP E1508 09 ...
Страница 314: ...314 Specifications Appendix A Thermocouple Type J SCPs HP E1501 02 03 ...
Страница 315: ...Specifications 315 Appendix A Thermocouple Type J SCPs HP E1508 09 ...
Страница 316: ...316 Specifications Appendix A Thermocouple Type K SCPs HP E1501 02 03 ...
Страница 317: ...Specifications 317 Appendix A Thermocouple Type R SCPs HP E1501 02 03 ...
Страница 318: ...318 Specifications Appendix A Thermocouple Type R SCPs HP E1508 09 ...
Страница 319: ...Specifications 319 Appendix A Thermocouple Type S SCPs HP E1501 02 03 ...
Страница 320: ...320 Specifications Appendix A Thermocouple Type S SCPs HP E1508 09 ...
Страница 321: ...Specifications 321 Appendix A Thermocouple Type T SCPs HP E1501 02 03 ...
Страница 322: ...322 Specifications Appendix A Thermocouple Type T SCPs HP E1508 09 ...
Страница 323: ...Specifications 323 Appendix A 5K Thermistor Reference SCPs HP E1501 02 03 ...
Страница 324: ...324 Specifications Appendix A 5K Thermistor Reference SCPs HP E1508 09 ...
Страница 325: ...Specifications 325 Appendix A RTD Reference SCPs HP E1501 02 03 ...
Страница 326: ...326 Specifications Appendix A RTD SCPs HP E1501 02 03 ...
Страница 327: ...Specifications 327 Appendix A RTD SCPs HP E1508 09 ...
Страница 328: ...328 Specifications Appendix A 2250 Thermistor SCPs HP E1501 02 03 ...
Страница 329: ...Specifications 329 Appendix A 2250 Thermistor SCPs HP E1508 09 ...
Страница 330: ...330 Specifications Appendix A 5K Thermistor SCPs HP E1501 02 03 ...
Страница 331: ...Specifications 331 Appendix A 5K Thermistor SCPs HP E1508 09 ...
Страница 332: ...332 Specifications Appendix A 10K Thermistor SCPs HP E1501 02 03 ...
Страница 333: ...Specifications 333 Appendix A 10K Thermistor SCPs HP E1508 09 ...
Страница 334: ...334 Specifications Appendix A Notes ...
Страница 346: ...346 Glossary Appendix C Notes ...
Страница 388: ...388 Generating User Defined Functions Appendix F Notes ...
Страница 438: ...438 Index Writing the algorithm 129 values to CVT elements 120 values to the FIFO 121 Z ZERO CALibration ZERO 194 ...