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1 FUNCTIONS

1.7 Communications Using MODBUS/TCP

107

1.7 Communications Using MODBUS/TCP

MODBUS/TCP is a protocol for using MODBUS protocol messages on a TCP/IP network.

The RJ71EN71 and RnENCPU (network part) support the MODBUS/TCP slave function so that they can communicate with

MODBUS/TCP master devices.

For communications using MODBUS/TCP, refer to the following.

 MELSEiQ-R MODBUS/TCP Reference Manual

• When this function is used on the RJ71EN71 or RnENCPU (network part), check the firmware version of the

module. ( Page 406 Added and Enhanced Functions)

• This function is not available when the network type is set to "Q Compatible Ethernet" for the RJ71EN71.

(1) MODBUS/TCP master device

(2) RJ71EN71 or RnENCPU (network part)

(1) (2)

Request message

Response message

Ethernet

Default Chapter3
- Design Precautions3
- Safety Precautions3
- Conditions of Use for the Product10
- Introduction10
- Table of Contents11
- Relevant Manuals15
- Terms16
Chapter 1 Functions19
Connection with MELSOFT Product and GOT19
- Connection Via a Hub19
SLMP Communications29
- Applications29
  - Data Read/Write29
  - File Read/Write29
- Communication Structure30
- Data Communication Procedures30
- List of Valid Commands32
- SLMP Reference Manual32
Communications Using the Predefined Protocol34
- Applicable Connections34
- Data Communication Procedures35
- Protocol Communication Type42
- Packet Elements43
- Execution Conditions of Predefined Protocol Communications50
- Example of Predefined Protocol Communications52
Socket Communications61
- Setting Procedure61
- List of Dedicated Instructions62
- Applicable Connections62
- Communication Structure63
- Communications Using TCP/IP64
- Communications Using UDP/IP67
- Precautions for UDP/IP Communications67
- Broadcast Communications68
- Precautions69
Communications Using the Fixed Buffer70
- Differences between the "Procedure Exist" and "No Procedure" Control Methods70
- Setting Procedure70
- Applicable Dedicated Instructions71
- Applicable Connections71
- Communication Structure71
- Send Procedure73
  - Procedure Exists73
  - No Procedure74
- Receive Procedure75
- Pairing Open79
- Broadcast Communications80
- Precautions80
- Data Format81
- Example of Communications Using the Fixed Buffer86
1.6 Communications Using the Random Access Buffer96
- Setting Procedure96
- Procedure for Reading from External Device97
- Communication Structure97
- Procedure for Writing from External Device98
- Physical Address and Logical Address of Random Access Buffer99
- Precautions99
- Data Format99
- Example of Communications with Random Access Buffer108
Communications Using MODBUS/TCP109
- Automatic Response Function110
- MODBUS Device Assignment Function111
- List of MODBUS Standard Functions117
Link Dedicated Instruction Communication118
- Applicable Dedicated Instructions118
- Data Communication Procedures119
File Transfer Function (FTP Server)120
- Data Communication Procedures121
- Files that Can be Transferred with FTP123
- FTP Command124
File Transfer Function (FTP Client)137
- File Transfer Specifications137
- Transferable Files138
- Procedure for Executing the File Transfer Function (FTP Client)139
- Precautions141
Time Setting Function (SNTP Client)143
- Communication Timeout144
- Delay by Communication Time144
- When Using Multi-CPU System Configuration144
Web Server Function145
- Javascript Objects146
- CGI Object160
- Error Message173
  - Display Example of Error Messages173
  - List of Error Messages of the User Web Page174
Security Function175
- IP Filter Function175
- Remote Password176
Simple CPU Communication Function (CPU Module (Built-In Ethernet Port Part))183
- Communication Pattern184
- Communication Setting and Execution Interval184
- Setting Procedure184
- Checking the Simple CPU Communication Status191
- Precautions193
- When the Communication Destination Is a Redundant System194
Simple CPU Communication Function (RJ71EN71, Rnencpu (Network Part))195
- Comm Patn196
- Setting Procedure196
  - Registration of Communication Destination197
  - Udp/Tcp198
- Checking the Simple CPU Communication Status209
- Precautions211
IP Address Change Function213
- IP Address of the Ethernet-Equipped Module214
- Usage Methods216
- Checking the IP Address219
- Checking the Operating Status219
- Precautions219
  - Write Processing and Clear Processing Execution Timing220
  - Communications by Network Number/Station Number220
Redundant System Function221
- System Configuration221
- System Switching Operation222
- System Switching Request to the Control System CPU Module223
- Redundant Group Setting225
  - Redundant Module Group Settings225
  - Port Group Setting226
- Communication Path Bypass Function227
- Both Systems Identical IP Address Setting Function228
  - Availability of Control System IP Address for each Function229
  - How to Use Dedicated Instructions229
- Functions Restricted in a Redundant System231
Chapter 2 Parameter Settings243
- Own Node Settings244
  - Communications by Network No./Station No.245
  - Enable/Disable Online Change245
- External Device Configuration246
- Existence Confirmation248
Setting Parameters243
Basic Settings243
Application Settings249
- RJ71EN71, Rnencpu (Network Part)249
- CPU Module (Built-In Ethernet Port Part)250
- Communication Speed252
- Frame Settings252
  - Jumbo Frame252
  - Current Password254
- FTP Server Settings254
  - FTP Timer Settings254
  - Password Setting254
- DNS Settings255
- FTP Client Settings255
  - Response Monitoring Timer255
  - CPU Response Monitoring Timer256
- MODBUS/TCP Settings256
- Device Assignment257
- Simple CPU Communication Setting (RJ71EN71, Rnencpu (Network Part))258
  - Execution Timing261
  - Specified Time (Hour, Minute, Day of Week)261
- Time Setting261
- Timer Settings for Data Communication262
  - Precautions for Settings263
  - Setting Value for each Timer of the External Device Side263
  - Number of Retries264
- Gateway Parameter Settings265
- IP Filter Settings265
- Security265
  - Gateway Information266
  - Gateway IP Address266
  - Subnet Address266
- Network/Station No. <-> IP Information Setting267
  - Setting System268
  - Automatic Response System269
  - IP Address Calculation Example270
  - IP Address Calculation System270
  - Table Conversion System271
  - Conversion Table Registration Example272
  - Combination System274
  - Conversion Settings274
  - Subnet Mask Pattern274
- Interrupt Settings275
- IP Packet Transfer Setting275
- Network Dynamic Routing276
- Module Operation Mode277
- Redundant System Settings278
- System B IP Address279
- Simple CPU Communication Setting (CPU Module (Built-In Ethernet Port Part))280
Chapter 3 Troubleshooting282
Checking with LED282
- When the ERROR LED or ERR LED Turns on or Is Flashing282
- When the RUN LED or READY LED Turns off282
- When Data Cannot be Received with the SD/RD LED off283
- When the L er LED Turns on283
- When the SD/RD LED Does Not Turn on at Data Sending283
Checking the Module Status284
- Error Information284
- Module Information List285
- Module Communication Test286
- Checking the Status and Result of Module Communication Test287
- Error Number When the Test Abnormally Ended287
Checking the Network Status288
- Ethernet Diagnostics288
- Simple CPU Communication Diagnostics296
- Communications Cannot be Performed with the External Device297
Troubleshooting by Symptom297
- Direct Connection to the Engineering Tool Is Not Possible299
- Communications Using the SLMP Cannot be Performed300
- CPU Module Search on the Network Cannot be Performed300
- Communications Using the Predefined Protocol Cannot be Performed301
- Communications Using the Random Access Buffer Cannot be Performed303
- A Response Message Cannot be Sent to the MODBUS/TCP Master Device304
- Communication Fails at MODBUS/TCP Connection304
- Communications Using MODBUS/TCP Cannot be Performed304
- A Dedicated Instruction Is Not Completed305
- Remote Password Does Not Work306
- The Access Cannot be Allowed/Denied Correctly by the IP Filter306
- Communications Using the Built-In Ethernet Port Are Slow307
- When the File Transfer Function (FTP Client) Is Used307
- When the Simple CPU Communication Function Is Used308
- The Update by Reading and Writing the Device Data Is Slow309
- System Switching Cannot be Performed Normally310
- When the Redundant System Function Is Used310
- Communication Fails at OPS Connection311
List of Error Codes312
List of Parameter Numbers329
- System Parameter329
Event List331
End Codes Returned to an External Device During Data Communications333
Appendices335
Appendix 1 Module Label335
- List of I/O Signals336
Appendix 2 I/O Signals336
- When the Network Type Is "Q Compatible Ethernet"337
- List of Buffer Memory Addresses338
Appendix 3 Buffer Memory338
- Buffer Memory Addresses Usable Only with RJ71EN71350
- When Using the RJ71EN71350
- Buffer Memory Addresses Not Supported by the RJ71EN71353
- Details of Buffer Memory Addresses (RJ71EN71, Rnencpu (Network Part))357
- Details of Buffer Memory Addresses (CPU Module (Built-In Ethernet Port Part))372
Appendix 4 Dedicated Instruction376
- File Transfer Function Instruction377
- Instruction for SLMP Communications377
- Instructions for Communications Using the Fixed Buffer377
- Socket Communications Instructions377
- Link Dedicated Instructions378
- Other Dedicated Instructions378
- Precautions for Dedicated Instructions379
Appendix 5 TCP/IP Communications, UDP/IP Communications380
- Communication Flow381
- Active Open Procedure382
- Open/Close Processing for Connection No.1382
- Passive Open Procedure383
- When "Do Not Open by Program" Is Set383
- When "Open by Program" Is Set384
- Open Procedure385
- UDP/IP Communications385
Appendix 6 Communications with Different Networks387
- When the Networks Consist of MELSEC Iq-R Series and Other Series388
- When the Networks Consist of Only MELSEC Iq-R Series388
- When the Networks Contain a Redundant System389
Appendix 7 Processing Time390
- Minimum Processing Time of Fixed Buffer Communications390
- Calculation Formula391
- Processing Time of Communications Using MODBUS/TCP391
- System Switching Time When a Redundant System Is Used392
- Timing Chart393
- Performance List of Simple CPU Communication Function394
- Module Parameter395
- Restricted Functions and Specifications395
Appendix 8 When Connecting the Module to a Remote Head Module395
Appendix 9 Port Numbers Used by Ethernet-Equipped Module396
- Operation Image of each Communication Type of Protocol397
- For "Send Only" Communication Type397
Appendix 10Operation Image and Data Structure of Predefined Protocol397
- For "Receive Only" Communication Type398
- When the Instruction Completed with an Error399
- For "Send & Receive" Communication Type400
- When the Instruction Completed Successfully400
- Verification Operation of Receive Packet402
  - When Multiple Receive Packets (Expected Packets) Are Specified402
  - When Received Data Are Matched with a Receive Packet402
- Example of Packet Element Data403
Appendix 11 Example of External Device Program406
Appendix 12How to Turn off ERR LED407
- Method Using a Dedicated Instruction407
- Method Using I/O Signals407
Appendix 13Added and Enhanced Functions408
Index410
- Revisions412
- Warranty413
- Trademarks414

Brand	Mitsubishi Electric
Model	MELSEC iQ-RJ71EN71
Category	Controller
Language	English

Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

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