Skip to Content

Changes for page 08 Communication

Last modified by Iris on 2025/07/24 15:23
From version 9.1
edited by Stone Wu
on 2022/08/30 09:58
Change comment: There is no comment for this version
To version 4.12
edited by Stone Wu
on 2022/07/07 15:28
Change comment: (Autosaved)

Summary

Details

Page properties
Parent
... ... @@ -1,1 +1,1 @@
1 -Servo.Manual.02 VD2 SA Series.WebHome
1 +Servo.1 User Manual.02 VD2 SA Series.WebHome
Content
... ... @@ -11,7 +11,7 @@
11 11  
12 12  Figure 8-1 The position of RS485 communication port of VD2B drive
13 13  
14 -For the position of the RS485 communication port of other models, see __[[4.5 Communication signal wiring>>https://docs.we-con.com.cn/bin/view/Servo/Manual/02%20VD2%20SA%20Series/04%20Wiring/#HCommunicationsignalwiring]]__.
14 +For the position of the RS485 communication port of other models, see __[[4.5 Communication signal wiring>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/04%20Wiring/#HCommunicationsignalwiring]]__.
15 15  
16 16  The servo drive adopts RS485 half-duplex communication mode. The 485 bus should adopt the hand-in-hand structure instead of the star structure or the bifurcated structure. The star structure or bifurcation structure will produce reflected signals, which will affect the 485 communication.
17 17  
... ... @@ -45,7 +45,7 @@
45 45  The VD2 series servo drives currently support the RTU communication format. The typical data frame format is shown in the table.
46 46  
47 47  (% class="table-bordered" %)
48 -|=(% rowspan="2" scope="row" style="text-align: center; vertical-align: middle; width: 425px;" %)**There should be a message interval not less than 3.5 characters at the beginning**|=(% style="text-align: center; vertical-align: middle; width: 166px;" %)**Address**|=(% style="text-align: center; vertical-align: middle; width: 189px;" %)**Function code**|=(% style="text-align: center; vertical-align: middle; width: 155px;" %)**Data**|=(% style="text-align: center; vertical-align: middle; width: 158px;" %)**CRC check code**
48 +|(% rowspan="2" style="text-align:center; vertical-align:middle; width:425px" %)**There should be a message interval not less than 3.5 characters at the beginning**|(% style="text-align:center; vertical-align:middle; width:166px" %)**Address**|(% style="text-align:center; vertical-align:middle; width:189px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:155px" %)**Data**|(% style="text-align:center; vertical-align:middle; width:158px" %)**CRC check code**
49 49  |(% style="text-align:center; vertical-align:middle; width:166px" %)1 byte|(% style="text-align:center; vertical-align:middle; width:189px" %)1 byte|(% style="text-align:center; vertical-align:middle; width:155px" %)N bytes|(% style="text-align:center; vertical-align:middle; width:158px" %)2 bytes
50 50  
51 51  == **Description of supported function codes** ==
... ... @@ -53,7 +53,7 @@
53 53  The host reads and writes data to the servo through Modbus RTU format (03, 06 function codes). The corresponding Modbus function codes are as follows:
54 54  
55 55  (% class="table-bordered" %)
56 -|=(% style="text-align: center; vertical-align: middle;" %)**Operate**|=(% style="text-align: center; vertical-align: middle;" %)**Command code**
56 +|(% style="text-align:center; vertical-align:middle" %)**Operate**|(% style="text-align:center; vertical-align:middle" %)**Command code**
57 57  |(% style="text-align:center; vertical-align:middle" %)Read 16-bit/32-bit function code|(% style="text-align:center; vertical-align:middle" %)0x03
58 58  |(% style="text-align:center; vertical-align:middle" %)Write 16-bit function code|(% style="text-align:center; vertical-align:middle" %)0x06
59 59  |(% style="text-align:center; vertical-align:middle" %)Write 32-bit function code|(% style="text-align:center; vertical-align:middle" %)0x10
... ... @@ -68,10 +68,9 @@
68 68  
69 69  Correct response format:
70 70  
71 -(% style="width:1055px" %)
72 -|(% rowspan="2" %)**Address**|(% rowspan="2" %)**Function code**|(% rowspan="2" style="width:279px" %)**Number of bytes of returned data**|(% colspan="2" style="width:274px" %)**Register 1**|(% rowspan="2" style="width:98px" %)**…**|(% rowspan="2" %)**CRC check code**
73 -|(% style="width:160px" %)**high byte**|(% style="width:114px" %)**low byte**
74 -|1 byte|03|(% style="width:279px" %)1 byte|(% style="width:160px" %)1 byte|(% style="width:114px" %)1 byte|(% style="width:98px" %)…|2 bytes
71 +|(% rowspan="2" %)**Address**|(% rowspan="2" %)**Function code**|(% rowspan="2" %)**Number of bytes of returned data**|(% colspan="2" %)**Register 1**|(% rowspan="2" %)**…**|(% rowspan="2" %)**CRC check code**
72 +|**high byte**|**low byte**
73 +|1 byte|03|1 byte|1 byte|1 byte|…|2 bytes
75 75  
76 76  **Write function code: 0x06**
77 77  
... ... @@ -91,8 +91,8 @@
91 91  
92 92  If the setting is successful, the original is returned
93 93  
94 -|(% rowspan="2" style="width:551px" %)**There should be a message interval not less than 3.5 characters at the beginning**|(% style="width:114px" %)**Address**|(% style="width:127px" %)**Function code**|(% style="width:104px" %)**Data**|(% style="width:180px" %)**CRC check code**
95 -|(% style="width:114px" %)1 byte|(% style="width:127px" %)1 byte|(% style="width:104px" %)N bytes|(% style="width:180px" %)2 bytes
93 +|(% rowspan="2" %)**There should be a message interval not less than 3.5 characters at the beginning**|**Address**|**Function code**|**Data**|**CRC check code**
94 +|1 byte|1 byte|N bytes|2 bytes
96 96  
97 97  (% style="color:inherit; font-family:inherit; font-size:26px" %)**CRC check**
98 98  
... ... @@ -151,13 +151,13 @@
151 151  == **Error response frame** ==
152 152  
153 153  (% class="table-bordered" %)
154 -|=(% style="text-align: center; vertical-align: middle;" %)**Address**|=(% style="text-align: center; vertical-align: middle;" %)**Function code**|=(% style="text-align: center; vertical-align: middle;" %)**Error code**|=(% style="text-align: center; vertical-align: middle;" %)**CRC check code**
153 +|(% style="text-align:center; vertical-align:middle" %)**Address**|(% style="text-align:center; vertical-align:middle" %)**Function code**|(% style="text-align:center; vertical-align:middle" %)**Error code**|(% style="text-align:center; vertical-align:middle" %)**CRC check code**
155 155  |(% style="text-align:center; vertical-align:middle" %)1 byte|(% style="text-align:center; vertical-align:middle" %)Command code+0x80|(% style="text-align:center; vertical-align:middle" %)Error code|(% style="text-align:center; vertical-align:middle" %)2 bytes
156 156  
157 157  When an error occurs, set the function code bit7 issued by the host to 1, and return (for example, 0x03 returns 0x83, 0x06 returns 0x86); the description of the error code are as follows.
158 158  
159 159  (% class="table-bordered" %)
160 -|=(% style="text-align: center; vertical-align: middle;" %)**Error code**|=(% style="text-align: center; vertical-align: middle;" %)**Coding description**
159 +|(% style="text-align:center; vertical-align:middle" %)**Error code**|(% style="text-align:center; vertical-align:middle" %)**Coding description**
161 161  |(% style="text-align:center; vertical-align:middle" %)0x0001|(% style="text-align:center; vertical-align:middle" %)Illegal command code
162 162  |(% style="text-align:center; vertical-align:middle" %)0x0002|(% style="text-align:center; vertical-align:middle" %)Illegal data address
163 163  |(% style="text-align:center; vertical-align:middle" %)0x0003|(% style="text-align:center; vertical-align:middle" %)Illegal data
... ... @@ -203,22 +203,6 @@
203 203  |**high byte**|**low byte**|**high byte**|**low byte**
204 204  |01|06|01|0A|0B|B8|AF, 76
205 205  
206 -**10 Function code write**
207 -
208 -P07-09 set the 1st segment position to 2000, and this variable corresponds to the Modbus address: 1801 (0x0709).
209 -
210 -Request format:
211 -
212 -|(% rowspan="2" %)**Address**|(% rowspan="2" %)**Function code**|(% colspan="2" %)**Initial address**|(% colspan="2" %)**Number of register**|(% rowspan="2" %)**Number of data**|(% colspan="2" %)**Data 1**|(% colspan="2" %)**Data 2**|(% colspan="2" %)**CRC check code**
213 -|**high byte**|**low byte**|**high byte**|**low byte**|**high byte**|**low byte**|**high byte**|**low byte**|**high byte**|**low byte**
214 -|01|10|07|09|00|02|04|00|00|07|D0|16|59
215 -
216 -The slave responds normally:
217 -
218 -|(% rowspan="2" %)**Address**|(% rowspan="2" %)**Function code**|(% colspan="2" %)**Register address**|(% colspan="2" %)**Data**|(% colspan="2" %)**CRC check code**
219 -|**high byte**|**low byte**|**high byte**|**low byte**|**high byte**|**low byte**
220 -|01|10|07|09|00|02|90|BE
221 -
222 222  = **Servo communication parameter setting** =
223 223  
224 224  (% style="text-align:center" %)
... ... @@ -226,26 +226,29 @@
226 226  
227 227  Figure 8-3 Modbus communication parameter setting process
228 228  
229 -**Set the servo address P12-1**
212 +**(1) Set the servo address P12-1**
230 230  
231 231  When multiple servos are in network communication, each servo can only have a unique address, otherwise it will cause abnormal communication and fail to communicate.
232 232  
233 -**Set the serial port baud rate P12-2**
216 +**(2) Set the serial port baud rate P12-2**
234 234  
235 235  The communication rate of the servo and the communication rate of the host computer must be set consistently, otherwise the communication cannot be carried out.
236 236  
237 -**Set the serial port data format P12-3**
220 +**(3) Set the serial port data format P12-3**
238 238  
239 239  The data bit check methods of servo communication are:
240 240  
241 -* Odd parity
242 -* Even parity
243 -* No parity
244 -* The stop bit: 1 stop bit and 2 stop bits.
224 +Odd parity
245 245  
226 +Even parity
227 +
228 +No parity
229 +
230 +The stop bit: 1 stop bit and 2 stop bits.
231 +
246 246  The data frame format of the servo and the host computer must be consistent, otherwise the communication cannot be carried out.
247 247  
248 -**Set that whether the function code changed by Modbus communication is written into EEPROM in real time [P12-4]**
234 +**(4) Set that whether the function code changed by Modbus communication is written into EEPROM in real time [P12-4]**
249 249  
250 250  When the host computer modifies the servo function code through communication, it can choose to store it in EEPROM in real time, which has the function of power-off storage.
251 251  
... ... @@ -257,7 +257,7 @@
257 257  |(% style="text-align:center; vertical-align:middle" %)[[image:image-20220611153214-3.png]]
258 258  |After the EEPROM is damaged, the servo will have an non resettable fault!
259 259  
260 -**Set the high and low order of the 32-bit monitoring data**
246 +**(5) Set the high and low order of the 32-bit monitoring data**
261 261  
262 262  Part of the monitoring volume is 32-bit length and occupies 2 consecutive bias numbers. The user needs to set the order of the data high bit and low bit correctly, otherwise it will cause data reading and writing errors!
263 263  
... ... @@ -266,42 +266,51 @@
266 266  The description of related function codes are as follows.
267 267  
268 268  (% class="table-bordered" %)
269 -|=(% style="text-align: center; vertical-align: middle; width: 121px;" %)**Function code**|=(% style="text-align: center; vertical-align: middle; width: 165px;" %)**Name**|=(% style="text-align: center; vertical-align: middle; width: 148px;" %)(((
255 +|(% style="text-align:center; vertical-align:middle; width:121px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:205px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:187px" %)(((
270 270  **Setting method**
271 -)))|=(% style="text-align: center; vertical-align: middle; width: 165px;" %)(((
257 +)))|(% style="text-align:center; vertical-align:middle; width:186px" %)(((
272 272  **Effective time**
273 -)))|=(% style="text-align: center; vertical-align: middle; width: 109px;" %)**Default value**|=(% style="text-align: center; vertical-align: middle; width: 85px;" %)**Range**|=(% style="text-align: center; vertical-align: middle; width: 224px;" %)**Definition**|=(% style="text-align: center; vertical-align: middle; width: 69px;" %)**Unit**
274 -|(% style="text-align:center; vertical-align:middle; width:121px" %)P12-02|(% style="text-align:center; vertical-align:middle; width:165px" %)Baud rate|(% style="text-align:center; vertical-align:middle; width:148px" %)(((
259 +)))|(% style="text-align:center; vertical-align:middle; width:130px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:132px" %)**Range**|(% style="text-align:center; vertical-align:middle; width:335px" %)**Definition**|(% style="text-align:center; vertical-align:middle; width:189px" %)**Unit**
260 +|(% style="text-align:center; vertical-align:middle; width:121px" %)P12-02|(% style="text-align:center; vertical-align:middle; width:205px" %)Baud rate|(% style="text-align:center; vertical-align:middle; width:187px" %)(((
275 275  Operation setting
276 -)))|(% style="text-align:center; vertical-align:middle; width:165px" %)(((
262 +)))|(% style="text-align:center; vertical-align:middle; width:186px" %)(((
277 277  Effective immediately
278 -)))|(% style="text-align:center; vertical-align:middle; width:109px" %)2|(% style="text-align:center; vertical-align:middle; width:85px" %)0 to 5|(% style="width:224px" %)(((
279 -* 0: 2400bps
280 -* 1: 4800bps
281 -* 2: 9600bps
282 -* 3: 19200bps
283 -* 4: 38400bps
284 -* 5: 57600bp
285 -)))|(% style="text-align:center; vertical-align:middle; width:69px" %)-
286 -|(% style="text-align:center; vertical-align:middle; width:121px" %)P12-03|(% style="text-align:center; vertical-align:middle; width:165px" %)Serial data format|(% style="text-align:center; vertical-align:middle; width:148px" %)(((
264 +)))|(% style="text-align:center; vertical-align:middle; width:130px" %)2|(% style="text-align:center; vertical-align:middle; width:132px" %)0 to 5|(% style="width:335px" %)(((
265 +0-2400bps
266 +
267 +1-4800bps
268 +
269 +2-9600bps
270 +
271 +3-19200bps
272 +
273 +4-38400bps
274 +
275 +5-57600bp
276 +)))|(% style="text-align:center; vertical-align:middle; width:189px" %)-
277 +|(% style="text-align:center; vertical-align:middle; width:121px" %)P12-03|(% style="text-align:center; vertical-align:middle; width:205px" %)Serial data format|(% style="text-align:center; vertical-align:middle; width:187px" %)(((
287 287  Operation setting
288 -)))|(% style="text-align:center; vertical-align:middle; width:165px" %)(((
279 +)))|(% style="text-align:center; vertical-align:middle; width:186px" %)(((
289 289  Effective immediately
290 -)))|(% style="text-align:center; vertical-align:middle; width:109px" %)0|(% style="text-align:center; vertical-align:middle; width:85px" %)0 to 3|(% style="width:224px" %)(((
291 -* 0: 1 stop bit, no parity
292 -* 1: 1 stop bit, odd parity
293 -* 2: 1 stop bit, even parity
294 -* 3: 2 stop bits, no parity
295 -)))|(% style="text-align:center; vertical-align:middle; width:69px" %)-
296 -|(% style="text-align:center; vertical-align:middle; width:121px" %)P12-04|(% style="text-align:center; vertical-align:middle; width:165px" %)Modbus communication data is written into EEPROM|(% style="text-align:center; vertical-align:middle; width:148px" %)(((
281 +)))|(% style="text-align:center; vertical-align:middle; width:130px" %)0|(% style="text-align:center; vertical-align:middle; width:132px" %)0 to 3|(% style="width:335px" %)(((
282 +0: 1 stop bit, no parity
283 +
284 +1: 1 stop bit, odd parity
285 +
286 +2: 1 stop bit, even parity
287 +
288 +3: 2 stop bits, no parity
289 +)))|(% style="text-align:center; vertical-align:middle; width:189px" %)-
290 +|(% style="text-align:center; vertical-align:middle; width:121px" %)P12-04|(% style="text-align:center; vertical-align:middle; width:205px" %)Modbus communication data is written into EEPROM|(% style="text-align:center; vertical-align:middle; width:187px" %)(((
297 297  Operation setting
298 -)))|(% style="text-align:center; vertical-align:middle; width:165px" %)(((
292 +)))|(% style="text-align:center; vertical-align:middle; width:186px" %)(((
299 299  Effective immediately
300 -)))|(% style="text-align:center; vertical-align:middle; width:109px" %)0|(% style="text-align:center; vertical-align:middle; width:85px" %)0 to 1|(% style="width:224px" %)(((
301 -* 0: Do not write to EEPROM, and do not store after power failure;
302 -* 1: Write to EEPROM, power-down storage.
303 -)))|(% style="text-align:center; vertical-align:middle; width:69px" %)-
294 +)))|(% style="text-align:center; vertical-align:middle; width:130px" %)0|(% style="text-align:center; vertical-align:middle; width:132px" %)0 to 1|(% style="width:335px" %)(((
295 +0: Do not write to EEPROM, and do not store after power failure;
304 304  
297 +1: Write to EEPROM, power-down storage.
298 +)))|(% style="text-align:center; vertical-align:middle; width:189px" %)-
299 +
305 305  = **Modbus communication variable address and value** =
306 306  
307 307  == **Variable address description** ==
... ... @@ -308,21 +308,24 @@
308 308  
309 309  Modbus registers are divided into two categories:
310 310  
311 -1. The first category is servo function code parameters (address: 0x0001 to 0x0D08), this part of the register is readable and writable (that is, 0x03 and 0x06 are supported);
312 -1. The second category is the monitoring volume of the servo (address: 0x1E01 to 0x2010), this part of the register is only readable (0x03 function is supported).
306 +~1. The first category is servo function code parameters (address: 0x0001 to 0x0D08), this part of the register is readable and writable (that is, 0x03 and 0x06 are supported);
313 313  
308 +2. The second category is the monitoring volume of the servo (address: 0x1E01 to 0x2010), this part of the register is only readable (0x03 function is supported).
309 +
314 314  **Servo function code representation: PXX-YY.**
315 315  
316 -* XX: represents the function code group number,
317 -* YY: represents the bias within the function code group;;
312 +XX: represents the function code group number,
318 318  
314 +YY: represents the bias within the function code group;;
315 +
319 319  During servo communication, the communication address of the function code is a 16-bit address, which is composed of the function code group number (high 8 bits) + group bias (low 8 bits), for example, the Modbus address corresponding to P12-1 (servo address) is 0x0C01.
320 320  
321 321  **Servo monitor volume representation: Uxx-yy.**
322 322  
323 -* xx: represents the monitoring volume group number,
324 -* yy: represents the bias within the monitoring volume group;
320 +xx: represents the monitoring volume group number,
325 325  
322 +yy: represents the bias within the monitoring volume group;
323 +
326 326  During Modbus communication, the starting address of the monitoring volume is 0x1E01, and the conversion relationship of the address is similar to the representation way of the function code.
327 327  
328 328  For example, U0-01 (servo status) corresponds to the Modbus address is 0x1E01.
... ... @@ -330,33 +330,35 @@
330 330  In order to facilitate actual use, this manual provides both decimal and hexadecimal address identification, it is shown in the following table:
331 331  
332 332  (% class="table-bordered" %)
333 -|=(% style="text-align: center; vertical-align: middle; width: 162px;" %)**Function code**|=(% style="text-align: center; vertical-align: middle; width: 302px;" %)(((
334 -**Modbus address (Hexadecimal)**
335 -)))|=(% style="text-align: center; vertical-align: middle; width: 278px;" %)(((
336 -**Modbus address (Decimal)**
337 -)))|=(% style="text-align: center; vertical-align: middle; width: 192px;" %)**Category**|=(% style="text-align: center; vertical-align: middle; width: 142px;" %)**Name**
338 -|(% style="text-align:center; vertical-align:middle; width:162px" %)P0-1|(% style="text-align:center; vertical-align:middle; width:302px" %)0x0001|(% style="text-align:center; vertical-align:middle; width:278px" %)1|(% style="text-align:center; vertical-align:middle; width:192px" %)Basic settings|(% style="text-align:center; vertical-align:middle; width:142px" %)Control mode
331 +|(% style="text-align:center; vertical-align:middle" %)**Function code**|(% style="text-align:center; vertical-align:middle" %)(((
332 +**Modbus address**
339 339  
340 -For detailed parameter addresses, please refer to __[["11.1 Lists of parameters".>>https://docs.we-con.com.cn/bin/view/Servo/Manual/02%20VD2%20SA%20Series/11%20Appendix/#HListsofparameters]]__
334 +**(Hexadecimal)**
335 +)))|(% style="text-align:center; vertical-align:middle" %)(((
336 +**Modbus address**
341 341  
338 +**(Decimal)**
339 +)))|(% style="text-align:center; vertical-align:middle" %)**Category**|(% style="text-align:center; vertical-align:middle" %)**Name**
340 +|(% style="text-align:center; vertical-align:middle" %)P0-1|(% style="text-align:center; vertical-align:middle" %)0x0001|(% style="text-align:center; vertical-align:middle" %)1|(% style="text-align:center; vertical-align:middle" %)Basic settings|(% style="text-align:center; vertical-align:middle" %)Control mode
341 +
342 +For detailed parameter addresses, please refer to __[["11.1 Lists of parameters".>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/11%20Appendix/#HListsofparameters]]__
343 +
342 342  == **Variable value type description** ==
343 343  
344 344  When writing function codes with signed numbers, you need to convert the pre-written data into hexadecimal complements. The conversion rules are as follows:
345 345  
346 -1. The data is positive or 0: complement code = original code
347 -1. The data is negative: complement code = 0xFFFF-absolute value of data + 0x0001
348 +~1. The data is positive or 0: complement code = original code
348 348  
349 -For example:
350 +2. The data is negative: complement code = 0xFFFF-absolute value of data + 0x0001
350 350  
351 -* The 16-bit signed positive number +100, the original code is 0x0064, and the complement is: 0x0064.
352 -* The 16-bit signed positive number -100, its hexadecimal complement is: 0xFFFF-0x0064 + 0x0001 = 0xFF9C.
353 -* If it is an unsigned number, just pass it directly according to its original code. For example, if the decimal number is 32768, write 0x8000 directly.
352 +For example,The 16-bit signed positive number +100, the original code is 0x0064, and the complement is: 0x0064. The 16-bit signed positive number -100, its hexadecimal complement is: 0xFFFF-0x0064 + 0x0001 = 0xFF9C.
354 354  
354 +If it is an unsigned number, just pass it directly according to its original code. For example, if the decimal number is 32768, write 0x8000 directly.
355 +
355 355  == **Numerical unit description** ==
356 356  
357 357  Some values have units and decimals, such as 0.1%, 0.1Hz, 0.01ms, and the corresponding value conversion is required when reading and writing. The methods are as follows:
358 358  
359 -1. When the unit is 0.1%: 1 represents 0.1%, 10 represents 1.0%, 1000 represents 100.0%. Therefore, writing 1000 means setting to 100.0%; on the contrary, if it is reading 1000, it means that the value is 100.0%;
360 -1. When the unit is 0.01ms: 1 means 0.01ms, 50 means 0.5ms, 10000 means 100ms. Therefore, writing 1000 means setting to 10.00ms; on the contrary, if 1000 is read, it means 10.00ms;
360 +~1. When the unit is 0.1%: 1 represents 0.1%, 10 represents 1.0%, 1000 represents 100.0%. Therefore, writing 1000 means setting to 100.0%; on the contrary, if it is reading 1000, it means that the value is 100.0%;
361 361  
362 -The other units can be deduced by this, and integer remains unchanged.
362 +2. When the unit is 0.01ms: 1 means 0.01ms, 50 means 0.5ms, 10000 means 100ms. Therefore, writing 1000 means setting to 10.00ms; on the contrary, if 1000 is read, it means 10.00ms; The other units can be deduced by this, and integer remains unchanged.