11 PID - Wecon

This instruction is to complete the PID operation and is used to control the parameters of the closed-loop control system. PID control has a wide range of applications in mechanical equipment, pneumatic equipment, constant pressure water supply and electronic equipment, etc. among them:

35

36

[[image:11_html_1c6bb88c06ac24cf.png||class="img-thumbnail"]] is the target value of PID control;

37

38

[[image:11_html_fb5122fb6e3a43d5.png||class="img-thumbnail"]] is the measured feedback value;

39

40

[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] The starting address of the buffer area for setting parameters required for PID operation and saving intermediate results, occupies a total of 26 variable units in the subsequent addresses, the value range is D0 to D7974, it is best to specify the power failure retention area, which will remain after the power is OFF Set the value, otherwise the buffer area needs to be assigned value before starting the operation for the first time. The function and parameter description of each unit are described in this section;

41

42

[[image:11_html_b126b1b2673dc1f4.png||class="img-thumbnail"]] is the storage unit of the PID calculation result. Please designate [[image:11_html_d47cd1f59b766ed3.png||class="img-thumbnail"]] as a non-battery holding area, otherwise it needs to be initialized and cleared before starting the calculation for the first time.

43

44

**Programming example**

45

46

(% style="text-align:center" %)

47

[[image:11_html_888504306151fa15.png||class="img-thumbnail"]]

48

49

The parameter description is as follows:

50

51

What is stored in D9 is the target value of PID adjustment, and D10 is the closed-loop feedback value. Note that D9 and D10 must be of the same dimension, such as both 0.01MPa units, or 1℃ units, etc.;

52

53

A total of 26 units of D200 to D225 are used to store the set value and process value of PID operation. These values must be set item by item before the first PID calculation;

54

55

The D130 unit is used to store the calculated control output value to control the execution of the action.

56

57

The function and setting method of the parameter value of each unit about starting of [[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] are described in the following table:

58

59

(% class="table-bordered" %)

60

|**Unit**|**Features**|**Setting instructions**

61

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]]|Sampling time (TS)|The setting range is 1 to 32767 (ms), but it needs to be greater than the PLC program scan period

62

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +1|Action direction (ACT)|(((

63

bit0: 0 = positive action; 1 = reverse action bit3: 0 = unidirectional; 1 = bidirectional

64

65

bit4: 0 = auto-tuning does not work; 1 = auto-tuning is executed, others cannot be used.

66

)))

67

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +2|Maximum ascent rate (DeltaT)|Setting range 0 to 32000 is the threshold of integral increment

68

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +3|Proportional gain (Kp)|Setting range 0 to 32767, note that this value is enlarged by 256 times, the actual value is Kp/256

69

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +4|Integral gain (Ki)|Setting range 0 to 32767, Ki=16384Ts/Ti, Ti is the integral time

70

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +5|Differential gain (Kd)|Setting range 0 to 32767, Kd≈Td/Ts, Td is the derivative time

71

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +6|Filtering (C0)|Setting range 0 to 1023, integral part filtering

72

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +7|Output lower limit|(((

73

Recommended setting range -2000 to 2000

74

75

{{id name="OLE_LINK630"/}}When bit3 of S3+1=0, set to 0; When bit3 of S3+1=1, set to -2000;

76

)))

77

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +8|Output upper limit|Recommended setting value 2000

78

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +9|Reserved|Reserved

79

|︙|︙|︙

80

|[[image:11_html_6c3fad4a32a3db43.png||class="img-thumbnail"]] +25|Reserved|Reserved

81

82

**Auto tuning example**

83

84

(% style="text-align:center" %)

85

[[image:11_html_c64303b9c6a47ae9.png||class="img-thumbnail"]]

**✎Note:**

● When multiple instructions are used, the device number of (d) cannot be repeated.

90

91

● During the execution of auto-tuning, the (s3) parameter space cannot be modified.

92

93

● The instruction occupies 26 point devices from the device specified in (s3).

94

95

● PID instruction can be used multiple times in the program and can be executed at the same time, but the variable area used in each PID instruction should not overlap; it can also be used in step instructions, jump instructions, timing interrupts, and subroutines, in this case When executing the PID instruction, the (s3)+9 cache unit must be cleared in advance.

96

97

● The maximum error of the sampling time Ts is -(1 operation cycle +1ms) +(1 operation cycle). If the sampling time Ts ≤ 1 operation cycle of the programmable controller, the following PID operation error (4D86H) will occur, and the PID operation will be executed with TS = operation cycle. In this case, it is recommended to use constant scan mode or use PID instruction in timer interrupt.

**Error code**

(% class="table-bordered" %)

102

|**Error code**|**Content**

103

|4085H|When the device specified in the read application instructions (s1), (s2), (s3), (d) exceeds the range of the corresponding device.

104

|4086H|When the device specified in the write application instruction (s3) and (d) exceeds the range of the corresponding device.

105

|4D80H|The sampling time is out of range.(T,,S,,≤0)

106

|4D81H|Input filter constant (,, ,,α ) is out of range (α<0 or α>1023)

107

|4D82H|The maximum ascent rate (△T) is out of range.(△T<0 or △T>1023)

108

|4D83H|The proportional gain (K//p//) is out of range.(K//p//<0)

109

|4D84H|The integral gain (K//i//) is out of range.(K//i//<0)

110

|4D85H|The differential gain (K//d//) is out of range.(K//d//<0)

111

|4D86H|The sampling time (T//s//) is less than the operation cycle.(T//s//<Scanning cycle)

**Example**

See manual.

== {{id name="_Toc32463"/}}{{id name="_Toc21837"/}}{{id name="_Toc31152"/}}**CCPID/CCPID calculation** ==

**CCPID**

This instruction is used to perform PID control that changes the output value according to the amount of input change.

122

123

-[CCPID (s1) (s2) (s3) (d)]

124

125

**Content, range and data type**

126

127

(% class="table-bordered" %)

128

129

|(s1)|Device number for storing the target value (SV)|-32767 to 32767|Signed BIN 16 bit|ANY16

130

|(s2)|Device number for storing the measured value (PV)|-32767 to 32767|Signed BIN 16 bit|ANY16

131

|(s3)|Device number for storing parameters|1 to 32767|Signed BIN 16 bit|ANY16

132

|(d)|Device number for storing output value (MV)|-32767 to 32767|Signed BIN 16 bit|ANY16

**Device used**

(% class="table-bordered" %)

137

|(% rowspan="2" %)**Instruction**|(% rowspan="2" %)**Parameter**|(% colspan="3" %)**Devices**|(((

138

**Offset modification**

)))|(((

**Pulse extension**

)))

|**D**|**R**|**SD**|**[D]**|**XXP**

143

|(% rowspan="4" %)CCPID|Parameter 1|●|●|●| |

144

|Parameter 2|●|●|●| |

145

|Parameter 3|●|●|●| |

146

|Parameter 4|●|●|●| |

**Features**

After setting target value (s1), measured value (s2), parameter (s3) to (s3) +12 and executing the program, the calculation result (MV) will be stored to the output according to the first sampling time (s3) in the parameter Value (d). For details, please refer to the user manual of "Wecon CC Series ccpid Function Description v1.4".

**✎Note:**

It can be executed multiple times at the same time (there is no limit to the number of loops), but please note that the device numbers (s3) and (d) used in the calculation cannot be repeated.

155

156

The instruction occupies 52 points of devices starting from the device specified in (s3).

157

158

During the execution of auto-tuning, the (s3) parameter space cannot be modified.

**Error code**

(% class="table-bordered" %)

163

|**Error code**|**Content**

164

|4085H|When the device specified in the read application instructions (s1), (s2), (s3), (d) exceeds the range of the corresponding device.

165

|4086H|When the device specified in the write application instruction (s3) and (d) exceeds the range of the corresponding device.

166

|4D80H|The sampling time is out of range.(T,,S,,≤0)

167

|4D81H|Input filter constant (α) is out of range (α<0 or α>1023)

168

|4D82H|The maximum ascent rate (△//T//) is out of range.(△//T//<0 or △//T//>1023)

169

|4D86H|The sampling time (Ts) is less than the operation cycle.(T//s//<Scanning cycle)

170

|4D87H|The proportional gain (K//p//) is out of range.(K//p//<1 or K//p//>32000)

171

|4D88H|The integral time constant (Ti) is out of range.(K//i//<0 or K//i//>3600)

172

|4D89H|The differential time constant (T//d//) is out of range.(K//d//<0 or K//d//>1000)

173

|4D90H|The upper limit of CCPID output is less than the lower limit.

**Example**

See "__CCPID Instruction Manual__".

178

179

== **{{id name="_Toc8661"/}}{{id name="_Toc13227"/}}{{id name="_Toc18478"/}}{{id name="_Toc29418"/}}{{id name="_Toc5268"/}}{{id name="_Toc5168"/}}{{id name="_Toc307"/}}FPID/FPID calculation** ==

**FPID**

The function of this instruction is to adjust PID control parameters by fuzzy algorithm.

184

185

-[FPID (s) (d1) (d2) (d3)]

186

187

**Content, range and data type**

188

189

(% class="table-bordered" %)

190

191

|(s)|Store the start number of the device of the fuzzy parameter table (no input required)|-|Signed BIN 16 bit|ANY16

192

|(d1)|Start number of the device storing the initialization parameters|-|Signed BIN 16 bit|ANY16

193

|(d2)|Store the start number of the device of the input PID parameter|-|Signed BIN 16 bit|ANY16

194

|(d3)|The start number of the device that stores the adjusted PID parameters|-|Signed BIN 16 bit|ANY16

**Device used**

(% class="table-bordered" %)

**Pulse extension**

)))

|**D**|**R**|**SD**|**LC**|**[D]**|**XXP**

203

|(% rowspan="4" %)FPID|Parameter 1|●|●|●|●| |

204

|Parameter 2|●|●|●|●| |

205

|Parameter 3|●|●|●|●| |

206

|Parameter 4|●|●|●|●| |

**Features**

This instruction needs to be used in conjunction with the PID instruction. It completes the fuzzy calculation of the adjustments of the three parameters of PID, Kp, Ki, and Kd. By passing in the three parameters of the PID, the new three parameters are calculated and substituted into the PID for output control.

211

212

**Parameter Description:**

213

214

(% class="table-bordered" %)

215

|(% colspan="6" %)**S parameter setting**

216

217

|Parameter 1|S|-|-|-|-

218

219

(% class="table-bordered" %)

220

|(% colspan="6" %)**d1 parameter setting**

|d1+1

|d1+3

|d1+5

|d1+7

|d1+9

|d1+11

|d1+13

|d1+15

|d1+17

|d1+19

|︙|︙|︙|︙|Reserved|-

(% class="table-bordered" %)

252

|(% colspan="6" %)**d2 parameter setting**

|Parameter 4|d2+3|Kp|16-bit integer|PID initial Kp value|-

258

|Parameter 5|d2+4|KI|16-bit integer|PID initial Ki value|-

259

|Parameter 6|d2+5|KD|16-bit integer|PID initial Kd value|-

|d2+9

|(% colspan="6" %)**d3 parameter setting**

|Parameter 4|d3+3|Kp|16-bit integer|Kp value of PID after adjustment|-

272

|Parameter 5|d3+4|KI|16-bit integer|Ki value of PID after adjustment|-

273

|Parameter 6|d3+5|KD|16-bit integer|Kd value of PID after adjustment|-

**✎Note:**

The instruction starts from the device specified in (d1) and occupies 38 points of the device, and initializes the parameters. Normally, it only needs to be initialized once before calling (some parameters are fixed) (occupies 38 words space).

280

281

The instruction starts with the device specified in (d2) and occupies 12 points of the device, input parameters, and input the first 6 parameters, where Kp, Ki, Kd are the initial values of the PID control parameters (occupies 12 words space) .

282

283

The instruction starts from the device specified in (d3) and occupies 8 points of soft elements and output parameters, among which Kp, Ki, Kd are the parameter values after fuzzy adaptive calculation, which can be input to the designated position of PID (occupy 8 words space).

284

285

The FPID instruction occupies 58 words. The address of each operand must have a specified interval interval, which cannot be occupied by other instructions.

**Error code**

(% class="table-bordered" %)

290

|**Error code**|**Content**

291

|4085H|When the device specified in the read application instructions (d1), (d2), (d3) exceeds the range of the corresponding device.

292

|4086H|When the device specified in the write application instructions (d1), (d2), (d3) exceeds the range of the corresponding device.

293

|4D91H|FPID calculation cycle is less than or equal to 0

294

|4D92H|FPID parameter range error

295

|4D93H|FPID initial flag error

**Example**

~1. Parameter d1

(% style="text-align:center" %)

302

[[image:11_html_93e9f66475d6eb0c.png||class="img-thumbnail"]]

2. Parameter d2

(% style="text-align:center" %)

307

[[image:11_html_548b859bc5568099.png||class="img-thumbnail"]]

3. Invoke FPID

(% style="text-align:center" %)

312

[[image:11_html_599ccfa817c379fd.png||class="img-thumbnail"]]

313

314

== **CCPID instruction introduction manual** ==

315

316

**Background and purpose**

(1) Background:

PID (proportion, integral, derivative) controller has been the earliest practical controller for nearly a hundred years, and it is still the most widely used industrial controller. The PID controller is simple and easy to understand, and does not require precise system models and other prerequisites in use, making it the most widely used controller.

(2) Purpose:

You might not be familiar with the parameter settings in the new series of CCPID for the first time, this manual could let you quickly understand the meaning of each parameter in the CCPID and the influence on the control effect, so that you can quickly learn the CCPID.

325

326

**Description of the host CCPID instruction**

327

328

**Instruction description**

329

330

**Content, range and data type**

331

332

(% class="table-bordered" %)

333

334

|CCPID|PID Operation|16|No|CCPID [[image:11_html_253eb1176b58e989.png]] [[image:11_html_80fccb1046bf8776.png]] [[image:11_html_8760537828f7beaf.png]] [[image:11_html_8b4fbd61f8ea9808.png]]|9

335

336

(% class="table-bordered" %)

337

338

|**D**|**R**|**SD**|**[D]**|**XXP**

339

|(% rowspan="4" %)CCPID|Parameter 1|●|●|●| |

340

|Parameter 2|●|●|●| |

341

|Parameter 3|●|●|●| |

342

|Parameter 4|●|●|●| |

**Device used**

[[image:11_html_954290ac172c672b.jpg||class="img-thumbnail"]] is the target value (SV) of PID control;

347

348

[[image:11_html_31f47ac5eec30067.jpg||class="img-thumbnail"]] is the measured feedback value (PV);

349

350

[[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] is the start address of the buffer area for setting parameters required for PID operation and saving intermediate results, occupying a total of 52 variable units of subsequent addresses (recommended to reserve 100 continuous spaces).The value range is D0 to D7,948, it is better to specify power failure retention, and the setting value remains after power supply is off. Otherwise,the buffer needs to be assigned value before starting the calculation for the first time. The function and parameter description of each unit are described in this section;

351

352

[[image:11_html_7e06d96423d5de52.jpg||class="img-thumbnail"]] is the storage unit (MV) of the PID calculation result. Please specify it as a non-battery retentive area, otherwise it needs to be initialized and cleared before the first start of calculation.

353

354

(% style="text-align:center" %)

355

[[image:11_html_8eeef07485b91193.jpg||class="img-thumbnail"]]

356

357

**Programming example**

358

359

The parameter description is as follows:

360

361

In D9, the target value of PID adjustment is stored, and D10 is the closed-loop feedback value. Note that D9 and D10 must be of the same dimension, such as both 0.01MPa units, or 1℃ units, etc.;

362

363

A total of 52 units of D200 to D224 are used to store the set value and process value of PID operation. These values must be set item by item before the first PID calculation;

364

365

D130 unit is used to store the calculated control output value to control the execution of the action.

366

367

The functions and setting methods of the parameter values of each unit used by [[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] are described in the following table:

368

369

[[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] to [[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] +14 is the parameter range that can be set (parameters set when CCPID is executed).

370

371

[[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] +15 to [[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] +21 is the space used internally by CCPID control.

372

373

[[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] +22 to [[image:11_html_6dcdd8fc88703a47.jpg||class="img-thumbnail"]] +51 is the parameter space used in the auto-tuning process.

374

375

(% class="table-bordered" %)

376

|**Unit**|**Features**|**Setting instructions**|**Supplement**

377

| |Sample time (TS)|The set range is 1 to 32,767 (ms), but greater than PLC program scan cycle.|It is how often the instruction calculates and updates the output value (MV). When TS is less than one scan time, PID instruction is executed with one scan time and alarm 4D86H. When TS ≤ 0, alarm 4D80H and no execution.

378

|+1|Action direction (ACT)|(((

379

bit0: 0=positive action; 1=reverse action bit2: auto-tuning transition zone switch. 0=not open;1=open

380

381

bit3: 0=unidirection; 1=bidirection

382

383

Bit4: 0=auto-tuning does not execute; 1=execute auto-tuning

384

385

[Bit6:0=Two-stage auto-tuning does not execute. 1=Execute two-stage auto-tuning (bit4 must be set to 1).

386

387

bit7: 0=Three-stage auto-tuning does not execute. 1=Execute three-stage auto-tuning (bit4 must be set to 1 )]

388

389

The Others cannot be used.

390

)))|(((

391

bit0: Positive action: similar heating system, when the temperature is lower than the set value, increases the output ; Reverse action: similar cooling system, when the temperature is greater than the set value, increases the output.

392

393

bit2: Self-tuning transition zone switch. There is a transition zone size of 1.5℃ when opened.

394

395

bit3: Bidirection indicates that outputs the positive and negative values to the heating system or the cooling system to control two external systems by one PID.

396

397

bit4: **✎**When bit4=1 and bit6 and bit7 are not 1, auto-tuning is not executed. **✎**When bit4=0 and one of bit6 and bit7 is 1, auto-tuning is not executed. **✎**When bit4=1 and bit6 and bit7 are both 1, auto-tuning is executed

398

)))

399

|+2|Filter coefficient|The first-order inertia filter of feedback amount (0 to 100%) has a range of 0 to100|When the value is greater than or equal to 100, it will be executed as 0, that is, no filtering will be executed;

400

|+3|Proportional gain(Kp)|Set range: 0 to 30,000[%]|Overrun error 4D87H

401

|+4|Integration time (Ti)|Ti is integration time, and the range is 0 to 3,600 (s)|Overrun error 4D88H

402

|+5|Differential time (Td)|Td is derivative time, and the range is 0 to 1,000 (s)|Overrun error 4D89H

403

|+6|Working interval|Operating temperature setting enabled by PID (0 indicates no effect) The range is 0 to 1,000|It is recommended to be greater than 5°C, that is, 50 (precision 0.1°C). If it exceeds the range, the boundary value will be taken.

404

|+7|Output low limit|(((

405

Range: -10,000 to 10,000.

406

407

Recommended setting range: -2,000 or 0 (when S3+1 bit3=0, the lower limit = 0;

408

409

when bit3=1, the lower limit = -2,000)

410

)))|(((

411

~1. Self-tuning initialization:

412

413

① Unidirection control: the lower limit is 0;

414

415

② Bidirection control: If the lower limit is greater than 0, adjust the lower limit to 0; if the upper limit and the lower limit are equal to 0, the default lower limit is -2,000. **✎**Note: If set to -2,000, and the output value (MV) is less than -2,000, it will output -2,000.

416

417

2. During the control process, the lower limit is dynamically adjustable. If the lower limit is greater than or equal to the upper limit, error 4D90H will be reported.

418

)))

419

|+8|Output upper limit|(((

420

Value range: -10,000 to 10,000.

421

422

Recommended setting value is 2,000

423

)))|(((

424

~1. Self-tuning initialization:

425

426

① Unidirection control: If the upper limit is less than 0, the default upper limit is 2,000;

427

428

② Bidirection control: If the upper limit is less than 0, adjust the upper limit to 0; if the upper limit and the lower limit are equal to 0, the default upper limit is -2,000. **✎**Note: If set to -2,000 and the output value (MV) is greater than -2,000, it will output 2,000.

429

430

2. During the control process, the upper limit is dynamically adjustable. If the lower limit is greater than or equal to the upper limit, error 4D90H will be reported.

)))

|+9|Mode setting|(((

0: Overshoot allowed

1: Slight overshoot or no overshoot

2: Dynamic setting

)))|(((

0:Overshoot allowed (ukd = 100)

440

441

1: Slight overshoot or no overshoot mode (ukd = 300)

)))

|+10|(((

Scale factor

(ukp)

)))|Typically sets value to 100 (default 100) [enabled when S3+9 is set to 2].The range is 1 to 500.|When the value is less than or equal to 0, or greater than 500, the boundary value will be taken.

448

|+11|Integral coefficient (uki)|Typically sets value to 50 (default 50) [enabled when S3+9 is set to 2]. The range is 1 to 300.|When the value is less than or equal to 0, or greater than 300, the boundary value will be taken.

449

|+12|Differential coefficient (ukd)|Typically sets value to 50 (default 100. 300 to 400 can be set when slight overshoot is required) [Enable when S3+9 is set to 2]. The range is 1 to 500.|When the value is less than or equal to 0, or greater than 500, the boundary value will be taken.

450

|+13|Maximum ascent rate (DeltaT)|The range is 0 to 32,000, which is the threshold of integral increment|Overrun error 4D82H

451

|+14|Filtering (C0)|The range is 0 to 1,023, integral part filtering|Overrun error 4D81H

452

|+15|(% rowspan="3" %)reserved for internal control|(% rowspan="3" %)Internal control space occupation|(% rowspan="3" %)

453

|┆

454

|+21

455

|+22|(% rowspan="3" %)used space for self-tuning|(% rowspan="3" %)New self-tuning space for internal use|(% rowspan="3" %)

|┆

|+51

1) The auto-tuning process occupies the space of S3+22 to S3+51. When the auto-tuning is successful, the adjusted parameters will be written into the space of S3+2 to S3+21.

460

461

2) +2 filter coefficient α: Processing in first-order inertial filter

462

463

Formula: **T,,now,,=(100-α)×T,,α,,+α×T,,old,,**

464

465

T,,α ,,is the currently measured temperature. T,,old ,,is the temperature that participated in the PID calculation last time. T,,now ,,is the temperature used for the current PID calculation. α is the filter coefficient (when α=0, no filtering is performed, and the range of α is 0 to 100.(If there is a temperature with a small overshoot but a long stabilization time, the parameter can be set to 80, and analyze the specific problems in detail)

466

467

3) +6 work range: Twork(example: 170 represents 17℃)

468

469

(% style="text-align:center" %)

470

[[image:11_html_7ab814bb49fffa5a.gif||class="img-thumbnail"]]

4) +9 working mode:

0: Working mode that allows overshoot

475

476

1: Slight overshoot or no overshoot working mode

477

478

2: Custom settings; to achieve by setting +10, +11, +12 three coefficients.

479

480

5) +1 bit2 self-tuning transition zone switch: (upper limit 1℃, low limit 0.5℃)

481

482

The transition zone description in forward control:

483

484

(% style="text-align:center" %)

485

[[image:11_html_d90c24627566bf2f.gif||class="img-thumbnail"]]

486

487

In the heating process, when PV≤SV+1℃, 100% power output; when PV＞SV+1℃, no output.

488

489

In the cooling process, when PV＜SV-0.5℃, 100% power output; When PV≥SV-0.5℃, no output.

490

491

The transition zone description in reverse control:

492

493

(% style="text-align:center" %)

494

[[image:11_html_d3c25044a54c62ce.gif||class="img-thumbnail"]]

495

496

In the cooling process, when PV≥SV-1℃, 100% power output; when PV＜SV-1℃, no output.

497

498

In the heating process, when PV＞SV+0.5℃, 100% power output; When PV≤SV+0.5℃, no output.

499

500

The transition zone description in bidirectional control:

501

502

(% style="text-align:center" %)

503

[[image:11_html_9eb35607c95b1580.gif||class="img-thumbnail"]]

504

505

In the heating process, when PV≤SV+1℃, 100% power heating output; when PV>SV+1℃, 100% power cooling output.

506

507

In the cooling process, when PV＜SV-0.5℃, 100% power heating output. When PV≥SV-0.5℃, 100% power cooling output

**Programming case**

**CCPID application configuration**

512

513

(1) Parameter setting

514

515

(% style="text-align:center" %)

516

[[image:11_html_36a152ee534a7f24.png||class="img-thumbnail"]]

517

518

(2) CCPID control process setting

519

520

(% style="text-align:center" %)

521

[[image:11_html_51d50fa8b154baca.png||class="img-thumbnail"]]

522

523

(% style="text-align:center" %)

524

[[image:11_html_66c8a636f6176c1f.png||class="img-thumbnail"]]

525

526

(3) Bidirection control

527

528

(% style="text-align:center" %)

529

[[image:11_html_234093eac2fe184d.png||class="img-thumbnail"]]

**✎Note:**

~1. CCPID is a special instruction for operation control. CCPID operation will be executed only after the sample time is reached.

534

535

2. There is no limit to the number of times the CCPID instruction can be used, but+51 cannot be repeated.

536

537

3. Before CCPID instruction is executed, CCPID parameters need to be set.

**Case analysis**

**(1) Control requirements**

542

543

The control environment of this example is a kettle. The configuration is controlled by PLC-5V2416 host with 4PT module, and PI8070 screen is used for data storage and process curve viewing.

544

545

**(2) Sample program**

546

547

(% style="text-align:center" %)

548

[[image:11_html_f0a22955a8da7129.png||class="img-thumbnail"]]

549

550

(% style="text-align:center" %)

551

[[image:11_html_ad08c65bd672c66e.png||class="img-thumbnail"]]

552

553

**(3) Parameter description**

554

555

(% class="table-bordered" %)

556

|**PLC device**|**Control instructions**

557

|M0|Set auto tuning

558

|M1|CCPID instruction calculation start

559

|M2|CCPID operating status

560

|Y0|Pulse output with adjustable pulse width

561

|D0|Temperature measured value

562

|D1|Temperature setting value

563

|D100|sample time

564

|D101|Control detail settings

565

|D102|First-order inertial filter coefficient

566

|D106|Working interval

567

|D109|Operating mode

568

569

**(4) Parameter control effect description**

570

571

1) Boiling water experiment

572

573

① Auto-tuning process and control process (no transition zone setting), take two-stage auto-tuning as an example

574

575

(% style="text-align:center" %)

576

[[image:11_html_9149b1e837158a17.gif||class="img-thumbnail"]]

577

578

Figure 1 Auto-tuning process curve without transition zone

579

580

When the control system is a single temperature control system or a system where environmental interference does not cause large fluctuations. Generally the automatic tuning without transition zone is selected, so that the self-tuning process can be completed more quickly than the method with transition zone.

581

582

②Self-tuning process and control process (transition zone setting)

583

584

(% style="text-align:center" %)

585

[[image:11_html_a1e8ad7a31bb04af.gif||class="img-thumbnail"]]

586

587

Figure 2 Self-tuning process curve with transition zone

588

589

It is more suitable in a two-way control system with transition zone self-tuning process. The transition zone has a range of 1.5°C. The upper limit is 1°C, and the lower limit is 0.5°C.

590

591

2) Difference in working interval setting

592

593

(% style="text-align:center" %)

594

[[image:11_html_4140432ce11883ad.gif||class="img-thumbnail"]]

595

596

Figure 3 Process curve under different working interval parameters

597

598

(% style="text-align:center" %)

599

[[image:11_html_f742d80c8cc95f35.gif||class="img-thumbnail"]]

600

601

Figure 4 Process curve without different working interval parameters (heating process diagram)

602

603

It can be seen from the partially enlarged graph that the parameters of the working interval have a certain influence on the overshoot and the stable time. In the case of allowing overshoot, setting the working interval parameters can make the overshoot smaller. This is because the deviation E of PID starting to work is relatively small, and the integration accumulation will not quickly saturate.

604

605

3) Result of filter coefficient setting

606

607

(% style="text-align:center" %)

608

[[image:11_html_815ec6c129ae3891.gif||class="img-thumbnail"]]

609

610

Figure 5 Process curve under different filtering parameters

611

612

The figure above is the experimental result under the small overshoot coefficient, the sample time is 1s. The coefficients of the first-order inertial filtering are (20, 50, 70, 80, 90). After adding the inertia coefficient, the stability time of system control is greatly accelerated, and it is increased by about 6 minutes for the boiling water experiment. The overshoot is about 1.2°C to 1.7°C.

613

614

Therefore, the introduction of first-order inertial filtering could greatly improve the PID environment where the temperature fluctuates to a certain extent and increase stabilization time.

615

616

**✎Note: **This parameter of filter coefficient is helpful for systems with not very large hysteresis or the control effect of the phenomenon that the control amount fluctuates back and forth has been greatly improved.

617

618

4) The difference in mode selection

619

620

0: Overshoot allowed(ukd = 100)

621

622

1: Small overshoot or no overshoot (ukd = 300)

623

624

(% style="text-align:center" %)

625

[[image:11_html_3a7b42c8f4672ce4.gif||class="img-thumbnail"]]

626

627

Figure 6 Process curves in different working modes

628

629

When selecting mode 1 (small overshoot or no overshoot), the stable temperature may be slightly higher than the set temperature (fluctuates above the set temperature).

630

631

5) The function of the coefficient

632

633

(% style="text-align:center" %)

634

[[image:11_html_74a7527eace55103.gif||class="img-thumbnail"]]

635

636

Figure 7 Process curve under dynamic setting

637

638

When selecting working mode 2, there are three corresponding adjustable parameters: ukp[S3+10], uki[S3+11], ukd[S3+12]. Usually, the default parameters can be used for ukp and uki. Adjust the value of ukd could achieve the control effect.

639

640

Ukp is adjusted when the value of Kp reaches the maximum value, and the default value is usually 100.

641

642

Uki is adjusted when periodic oscillations occur. Gradually increase the value of uki to track the control effect.

Wiki source code of 11 PID