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Receiving Explicit Messages

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Section 9-2

Bit

7

6

5

4

 

3

2

1

0

 

 

 

 

 

 

 

 

-

-

-

 

-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Operation status

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Unspecified

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0: Stopped (User program is not being executed.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1: Operating (User program is being executed.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Flash memory access status (CS1H, CJ1-H,CJ1M, and CS1D only)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0: Memory is not being written.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1: Memory is being written.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Battery status (CS1H, CJ1-H,CJ1M, and CS1D only)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0: No battery

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1: Battery installed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CPU status

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0: Normal

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1: CPU standby (waiting for SYSMAC Bus Remote I/O or other event)

Operating mode: Returns the operating mode of the CPU Unit in1-byte(2-digit)hexadecimal.

0001 Hex: PROGRAM mode; 0002 Hex: MONITOR mode;

0004 Hex: RUN mode

Fatal error information: Returns the fatal error information for the CPU Unit in 2 bytes (low to high).

1:System error (FALS)

1:Cycle time over

1:Program error

1:I/O setting error

1:No. of I/O points exceeded

1:Inner Board fatal error

1:Number duplicate use error

1:I/O Bus error

1:Memory error

Non-fatal error information: Returns thenon-fatalerror information for the CPU Unit in 2 bytes (low to high).

Unspecified (reserved for system use) 1: Special I/O Unit error

1: CPU Bus settings error

1:Battery error

1:SYSMAC BUS error

1:Special I/O Unit

1:CS1-seriesCPU Bus Unit error

1:Inner Board error

1:I/O verification error

1:PLC system error

1:Unspecified (reserved for system use)

1:Basic I/O Unit error

1:Interrupt task error

1:Unspecified (reserved for system use)

1:System error (FAL)

255

Receiving Explicit Messages

Section 9-2

Message Exists/Does Not Exist: When the MSG instruction is executed by the CPU Unit, the bit corresponding to the message number will turn ON and be returned in 2 bytes (from low to high bytes).

Message No. 0 (1: exists; 0: does not exist)

Message No. 1 (1: exists; 0: does not exist)

Message No. 2 (1: exists; 0: does not exist)

Message No. 3 (1: exists; 0: does not exist)

Message No. 4 (1: exists; 0: does not exist)

Message No. 5 (1: exists; 0: does not exist)

Message No. 6 (1: exists; 0: does not exist)

Message No. 7 (1: exists; 0: does not exist)

Error Code: The highest priority error code of the errors existing when the command is executed will be returned in2-bytedecimal (from low to high bytes). If there are no errors, the error code will be 0000.

Note For information on the severity of error codes, refer to theCS1 Series CPU Unit Operation Manual (W339) or theCJ Series CPU Unit Operation Manual (W393).

Error Messages: If the above error codes have occurred when FAL/FALS instructions are executed with registered messages, those messages are returned in16-byteASCII. If there are no registered messages or if the error codes have not occurred due to execution of FAL/FALS instructions, the code is returned in ASCII with 20 Hex (space) in 16 bytes.

Byte Data Read (Service Code: 1C Hex)

Byte Data Read reads any I/O memory area data in a CPU Unit. The read word data is in byte units. The response block data is returned in low-to-highbyte order.

Command Block

1C

C4

 

 

 

 

 

 

 

The class ID depends on the unit version.

(2F)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Version 2.0: The class ID is C4.

 

 

(*)

 

(*)

 

 

 

 

 

 

 

 

 

 

 

Version 1.0: The class ID is 2F.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Address L

No. of bytes read

 

 

 

 

 

 

 

Class ID

 

Service Code

 

 

Address H

 

 

 

 

 

 

 

 

 

 

 

 

Instance ID

Note A body format of either 8 bits or 16 bits is possible.

Response Block

 

 

9C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Service Code

Word data L

 

 

 

Word data L

 

 

Word data H

Word data H

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Read data (200 bytes max.)

Parameters

Service code (command, response): 1C Hex is specified for commands.

 

For responses, the highest bit will turn ON and 9C Hex will be returned.

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Section 9-2

Class ID (command): Always C4 (2F).

The class ID depends on the unit version. The class ID is C4 for unit version 2.0, and 2F for unit version 1.0.

Instance ID (command): The memory area that will read the data is specified as shown in the following table.

Instance ID (Hex)

CPU Unit memory area

Word range

 

for read

 

 

 

 

01

CIO

0000 to 6143

 

 

 

03

DM

D00000 to D32767

 

 

 

04

WR

W000 to W511

 

 

 

05

HR

H000 to H1535

 

 

 

08 to 20

EM, banks 0 to 18

En_00000 to En_32767

 

 

(n: 0 to 18)

 

 

 

 

Address L, Address H (command): The address of the first word from which

 

to read the data is specified in hexadecimal as shown below.

 

Address L: The lower 2 digits when the first word address is given in 4-digit

 

hexadecimal.

 

Address H: The higher 2 digits when the first word address is given in 4-digit

 

hexadecimal.

 

No of Read Bytes (command): The number of bytes of read data is specified

 

in 1-byte(2-digit)hexadecimal. The range is 01 to C8 Hex (1 to 200 decimal).

 

No. of bytes received (response): The number of bytes received from the

 

destination node address (remote node) is returned in hexadecimal.

 

Destination node address (response): The node address of the CS/CJ-

 

series EtherNet/IP Unit or built-inEtherNet/IP port that returned the response

 

is returned in hexadecimal.

 

Read data (response): The specified area, word, and byte data is returned in

 

order from word H (high byte: bits 8 to 15) to word L (low byte: bits 0 to 7). If

 

an odd number is specified for the number of read bytes, the last 1 byte of

 

data will be read to the high word.

Important Points

The actual address L, address H, and number of read bytes that can be spec-

 

ified depends on the model of the CPU Unit, and the data area being read. Do

 

not exceed the boundary of the data areas for the PLC you are using.

Word Data Read (Service Code: 1D Hex)

Word Data Read reads I/O memory area data in a CPU Unit. The read word data is in word units. The response block data is returned in low-to-highbyte order.

Command Block

1D

C4

 

 

 

 

(2F)

(*)

 

 

 

 

(*)

 

 

 

The class ID depends on the unit version. Version 2.0: The class ID is C4.

Version 1.0: The class ID is 2F.

Class ID Address L

No. of words read

 

Service Instance ID Address H

Code

 

Note A body format of either 8 bits or 16 bits is possible.

257

Receiving Explicit Messages

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Section 9-2

Response Block

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9D

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Service Code

Word data H

 

 

 

Word data H

 

 

 

Word data L

Word data L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Read data (200 bytes max.)

 

Parameters

Service code (command, response): ID Hex is specified for commands. For

 

responses, the highest bit will turn ON and 9D Hex will be returned.

 

Class ID (command): Always C4 (2F).

 

 

The class ID depends on the unit version. The class ID is C4 for unit version

 

2.0, and 2F for unit version 1.0.

 

 

Instance ID (command): The type of memory area that will read the data is

 

specified as shown in the following table.

 

 

 

 

 

 

 

 

 

Instance ID (Hex)

 

CPU Unit memory area

Word range

 

 

 

 

 

 

 

 

 

 

 

 

 

for read

 

 

 

 

 

 

 

 

 

 

 

 

 

 

01

 

 

 

 

 

 

 

 

CIO

0000 to 6143

 

 

 

 

 

 

 

 

 

 

 

 

 

03

 

 

 

 

 

 

 

 

DM

D00000 to D32767

 

 

 

 

 

 

 

 

 

 

 

 

 

04

 

 

 

 

 

 

 

 

WR

W000 to W511

 

 

 

 

 

 

 

 

 

 

 

 

 

05

 

 

 

 

 

 

 

 

HR

H000 to H1535

 

 

 

 

 

08 to 20

EM, banks 0 to 18

En_00000 to En_32767

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(n: 0 to 18)

 

 

 

 

 

Address L, Address H (command): The address of the first word to read the

 

data from is specified in hexadecimal as shown below.

 

Address L: The lower 2 digits when the first word address is given in 4-digit

 

hexadecimal.

 

 

 

 

 

 

 

 

 

 

Address H: The higher 2 digits when the first word address is given in 4-digit

 

hexadecimal.

 

 

 

 

 

 

 

 

 

 

No of Read Words (command): The number of words of read data is speci-

 

fied in 1-byte(2-digit)hexadecimal. The range is 01 to 64 Hex (1 to 100 deci-

 

mal).

 

 

 

 

 

 

 

 

 

 

Read data (response): The specified area, word, and byte data is returned in

 

order from word L (low byte: bits 0 to 7) to word H (high byte: bits 8 to 15).

Important Points

The actual address L, address H, and number of write data bytes that can be

 

specified depends on the model of the CPU Unit, and the data area being

 

written. Do not exceed the boundary of the data areas for the PLC you are

 

using.

 

 

 

 

 

 

 

 

 

Byte Data Write (Service Code: 1E Hex)

Byte Data Write writes data to an I/O memory area in a CPU Unit. The write word data is in byte units. The command block is specified in high-to-lowbyte order, as shown in the following diagram.

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Receiving Explicit Messages

Section 9-2

Command Block

1E

 

C4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(2F)

 

(*)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(*)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Class ID

Address L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Word data L

 

 

Word data L

Service Instance ID Address H

 

 

 

 

 

 

Code

 

 

 

Word data H

Word data H

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The class ID depends on the unit version. Version 2.0: The class ID is C4.

Version 1.0: The class ID is 2F.

Write data (200 bytes max.)

Note A body format of either 8 bits or 16 bits is possible.

Response Block

9E

Service Code

Parameters Service code (command, response): IE Hex is specified for commands. For responses, the highest bit will turn ON and 9E Hex will be returned.

Class ID (command): Always C4 (2F).

The class ID depends on the unit version. The class ID is C4 for unit version 2.0, and 2F for unit version 1.0.

Instance ID (command): The type of memory area to which the data will be written is specified as shown in the following table.

Instance ID (Hex)

CPU Unit memory area

Word range

 

for write

 

 

 

 

01

CIO

0000 to 6143

 

 

 

03

DM

D00000 to D32767

 

 

 

04

WR

W000 to W511

 

 

 

05

HR

H000 to H1535

 

 

 

08 to 20

EM, banks 0 to 18

En_00000 to En_32767

 

 

(n: 0 to 18)

 

Address L, Address H (command): The address of the first word to which

 

the data will be written is specified in hexadecimal as shown below.

 

Address L: The lower 2 digits when the first word address is displayed in 4-

 

digit hexadecimal.

 

Address H: The higher 2 digits when the first word address is displayed in 4-

 

digit hexadecimal.

 

Write data (response): The specified area and write data is returned in order

 

from word H (higher byte: bits 8 to 15) to word L (lower byte: bits 0 to 7). For

 

byte data write, specify an even number.

Important Points

The actual address L, address H, and number of write data bytes that can be

 

specified depends on the model of the CPU Unit, and the data area being

 

written. Do not exceed the boundary of the data areas for the PLC you are

 

using.

Word Data Write (Service Code: 1F Hex)

Word Data Write writes data to any I/O memory area in a CPU Unit. The write word data is in word units. The response block data is returned in low-to-highbyte order.

259

Receiving Explicit Messages

Section 9-2

Command Block

1F

 

C4

 

 

 

 

 

 

 

 

 

(2F)

 

(*)

 

 

 

 

 

 

 

 

 

(*)

 

 

 

 

 

 

 

 

 

Class ID

Address L

 

Word data H

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Service Instance ID Address H

Code

Word data L

 

The class ID depends on the unit version.

Version 2.0: The class ID is C4.

Version 1.0: The class ID is 2F.

Word data H

Word data L

Write data (200 bytes max.)

Note A body format of either 8 bits or 16 bits is possible.

Response Block

9F

Service Code

Parameters Service code (command, response): IF Hex is specified for commands. For responses, the highest bit will turn ON and 9F Hex will be returned.

Class ID (command): Always C4 (2F).

The class ID depends on the unit version. The class ID is C4 for unit version 2.0, and 2F for unit version 1.0.

Instance ID (command): The memory area to which the data is written is specified as shown in the following table.

 

Instance ID (Hex)

CPU Unit memory area

Word range

 

 

for write

 

 

 

 

 

 

01

CIO

0000 to 6143

 

 

 

 

 

03

DM

D00000 to D32767

 

 

 

 

 

04

WR

W000 to W511

 

 

 

 

 

05

HR

H000 to H1535

 

 

 

 

 

08 to 20

EM, banks 0 to 18

En_00000 to En_32767

 

 

 

(n: 0 to 18)

 

Address L, Address H (command): The address of the first word to which

 

the data is written is specified in hexadecimal as shown below.

 

Address L: The lower 2 digits when the first word address is displayed in 4-

 

digit hexadecimal.

 

 

 

Address H: The higher 2 digits when the first word address is displayed in 4-

 

digit hexadecimal.

 

 

 

Write data (response): The specified area and write data is returned in order

 

from word L (lower byte: bits 0 to 7) to word H (higher byte: bits 8 to 15).

Important Points

The actual address L, address H, and number of write data bytes that can be

 

specified depends on the model of the CPU Unit, and the data area being

 

written. Do not exceed the boundary of the data areas for the PLC you are

 

using.

 

 

260

SECTION 10

Communications Performance and Communications Load

This section describes the communications performance in an EtherNet/IP network, and shows how to estimate the I/O response times and transmission delays.

10-1 Communications System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

262

10-1-1 Tag Data Link Communications Method . . . . . . . . . . . . . . . . . . . . .

262

10-1-2 Calculating the Number of Connections. . . . . . . . . . . . . . . . . . . . . .

264

10-1-3 Network Transmission Delay Time . . . . . . . . . . . . . . . . . . . . . . . . .

265

10-2 Adjusting the Communications Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

268

10-2-1 Checking Bandwidth Usage for Tag Data Links . . . . . . . . . . . . . . .

269

10-2-2 Tag Data Link Bandwidth Usage and RPI . . . . . . . . . . . . . . . . . . . .

270

10-2-3 Adjusting Device Bandwidth Usage. . . . . . . . . . . . . . . . . . . . . . . . .

271

10-2-4

Changing the RPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

272

10-2-5

RPI Setting Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

276

10-3 I/O Response Time in Tag Data Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

283

10-3-1 Timing of Data Transmissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

283

10-3-2 EtherNet/IP Unit or CJ2H Built-in Port Data Processing Time . . . .

283

10-3-3 Effect on the CPU Unit’s Cycle Time. . . . . . . . . . . . . . . . . . . . . . . .

284

10-3-4 Tag Data Link I/O Response Time Calculation Example. . . . . . . . .

285

10-4 Tag Data Link Performance for CJ2M Built-in EtherNet/IP Ports . . . . . . . . .

291

10-4-1 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

291

10-4-2 Tag Data Link I/O Response Time . . . . . . . . . . . . . . . . . . . . . . . . . .

292

10-5 Message Service Transmission Delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

294

10-5-1 Maximum Transmission Delays (Excluding Delays in the Network)

294

261

Communications System

Section 10-1

10-1Communications System

10-1-1Tag Data Link Communications Method

Packet Interval (RPI)

Settings

In EtherNet/IP tag data links, the data transmission period is set for each connection as the packet interval (RPI). The target device will send data (i.e., output tags) once each packet interval (RPI), regardless of the number of nodes. Also, the heartbeat frame is sent from the originator to the target for each connection. The target uses the heartbeat to check to see if errors have occurred in the connection with the originator. The data transmission period of the heartbeat frame depends on the packet interval (RPI) settings.

Heartbeat Frame Transmission Period

Packet interval < 100 ms

The heartbeat frame transmission period is 100 ms.

Packet interval 100 ms

The heartbeat frame transmission period is the same as the RPI.

Example

In this example, 2 tag data link connections are set for node 2 (the originator) and node 1 (the target).

The packet interval (RPI) for output data 1 is set to 10 ms.

The packet interval (RPI) for output data 2 is set to 15 ms.

In this case, output data 1 is sent from node 1 to node 2 every 10 ms, and output data 2 is sent from node 1 to node 2 every 15 ms, as shown in the following diagram. Also, data is sent from node 2 (the originator) to node 1 (the target) with a heartbeat of 100 ms for connection 1 and a heartbeat of 100 ms for connection 2.

 

 

 

Node 1

 

 

 

Node 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Target

 

 

 

 

 

 

 

Output data 1

 

 

 

Originator

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Connection 1 heartbeat

 

100-msinterval

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10 ms

 

 

 

 

 

Output data 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Connection 2 heartbeat

100-msinterval

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Output data 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15 ms

10 ms

Output data 2

Output data 1

262

Communications System

Section 10-1

Packet Interval (RPI) and Bandwidth Usage (PPS)

In a tag data link, the number of packets transferred each second is called the bandwidth used or PPS (packets per second).

The PPS is calculated from the RPI and heartbeat as follows for each connection:

PPS used in a connection (pps)

= (1,000 RPI (ms)) + (1,000 Heartbeat transmission period (ms))

The following equation is used to calculate the total number of packets transferred by each EtherNet/IP Unit or built-inEtherNet/IP port in 1 second.

Unit’s total PPS = Total PPS of originator connections

+ Total PPS of target connections (See note.)

Note Connections set as target connections must be added, too.

The maximum number of packets that the Unit can transfer in 1 second (called the allowed Unit bandwidth) is 6,000 pps (CJ2M: 3,000 pps), so set the connection below this maximum value.

Example

Node 1 has both originator and target connections, with send RPI of 200 ms and 2 ms, and receive RPI of 1 ms.

Node 2 has originator connections only, with receive RPI of 200 ms, 2 ms, and 5 ms.

Node 3 has target connections only, with send RPI of 5 ms and 1 ms.

 

 

 

 

Node 1

 

 

 

O: Originator

 

 

 

 

 

O

 

 

T: Target

 

 

T

 

T

 

 

 

 

 

HB: Heartbeat

 

RPI: 200 ms

 

 

 

 

 

 

 

 

 

 

 

 

 

HB: 200 ms

 

 

 

 

RPI: 1 ms

 

 

 

 

 

 

 

 

 

 

RPI: 2 ms

 

 

HB: 100 ms

 

 

 

 

 

 

 

 

 

 

HB: 100 ms

 

 

 

 

O

O

 

 

 

 

T

Node 2

O

 

RPI:5ms

 

 

Node 3

 

 

 

 

 

T

 

 

 

 

 

 

 

 

 

 

 

 

HB:100ms

 

 

 

 

Each node’s total PPS is calculated as follows.

Total PPS of node 1 Unit

= 1,000 / 200 ms + 1,000 / 2 ms + 1,000 / 1 ms (for data)

+1,000 / 200 ms + 1,000 / 100 ms + 1,000 / 100 ms (for heartbeat)

=1,530 pps

Total PPS of node 2 Unit

=1,000 / 200 ms + 1,000 / 2 ms + 1,000 / 5 ms (for data)

+1,000 / 200 ms + 1,000 / 100 ms + 1,000 / 100 ms (for heartbeat)

=730 pps

Total PPS of node 3 Unit

=1,000 / 5 ms + 1,000 / 1 ms (for data)

+1,000 / 100 ms + 1,000 / 100 ms (for heartbeat) = 1,220 pps

All of the Units are within the allowed Unit bandwidth of 6,000 pps (CJ2M: 3,000 pps), so they can transfer data.

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10-1-2Calculating the Number of Connections

The maximum number of connections for the Unit is 32 for the CJ2M and 256 for other CPU Units.

The number of connections must be set to 32 or less for the CJ2M and 256 or less for other CPU Units combining both connections that the Unit opens as the originator and connections that are opened from an originator with the Unit as the target.

Example

Node 1 opens two connections as the target with node 2 and one connection as the originator with node 3. Therefore, the total is three connections. Node 2 opens two connections as the originator with node 1 and one connection as the target with node 3. Therefore, the total is three connections. Node 3 opens one connection as the target with node 1 and one connection as the target with node 2. Therefore, the total is two connections. In either case, the connections can be opened because the maximum number of connections for the Unit is less than 32 for the CJ2M and less than 256 for other CPU Units.

Node 1

O: Originator

T: Target

 

 

T T O

O

O

T

 

Node 2

Node 3

 

O

T

Also, if multicast is set, one packet will be sent, but the number of connections will be consumed.

Example

Node 3 sends one multicast packet to node 1 and node 2. At that time, node 3 opens one connection as the target with node 1 and one connection as the target with node 2 for a total of two connections. Caution is required because the number of connections consumed is the same as for unicast connections even when multicast connections are set.

Node 1

O: Originator

T: Target

O

Multicast

 

Multicast

T

Node 2

Node 3

 

O

 

T

264

Communications System

Section 10-1

10-1-3Network Transmission Delay Time

In an EtherNet/IP network, the tag data link packets are sent once each packet interval (RPI), but several delays occur between the transmission of packets from each node and the arrival of the packets at the destination nodes. The following diagram shows the 4 major delay sources.

Total network transmission delay = (1) Send processing delay + (2) Cable delays + (3) Switching hub delay + (4) Receive processing delay

(1) Send

EtherNet/IP

EtherNet/IP

(4) Receive

Unit

Unit

processing

processing

delay

 

 

delay

 

 

Data

 

 

Switching hub

 

 

 

(2) Cable delay (3) Switching hub delay

(2) Cable delay

 

1. Send Processing

Delay

The lengths of these delays depend on many factors, such as the tag data link connection settings (number of connections and data sizes), number of nodes, the switching hub being used, and cable lengths. Each delay is described in detail below.

The send processing delay is the delay that occurs within the EtherNet/IP Unit or built-inEtherNet/IP port when data packets are sent once each packet interval. This delay varies with the RPI error shown in the following graph, so the send processing time is the maximum value for each RPI.

Packet interval (RPI)

RPI error (±) (%)

0.5 to 1,000 ms

15 − (RPI (ms) ÷ 100)

 

 

1,000 ms to 10,000 ms

5% of the RPI

 

 

2. Cable Delay

 

16

 

 

 

 

 

 

 

 

 

 

 

14

 

 

 

 

 

 

 

 

 

 

 

12

 

 

 

 

 

 

 

 

 

 

(±)[%]

10

 

 

 

 

 

 

 

 

 

 

8

 

 

 

 

 

 

 

 

 

 

error

 

 

 

 

 

 

 

 

 

 

6

 

 

 

 

 

 

 

 

 

 

RPI

 

 

 

 

 

 

 

 

 

 

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

RPI [ms]

The cable delay is the time required for the data signal to pass through the cable and reach the destination. When an STP (shielded twisted-pair)cable of category 5, 5e, or higher is being used, the maximum cable delay is 545 ns/ 100 m. The cable delay represents a very small percentage of the total tag data link delay.

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3. Switching Hub

Delay

4. Receive Processing

Delay

Example Calculation

of the Tag Data Link

Delay

The switching hub delay is the delay time between the arrival of the packet at the switching hub and the output of the packet from the hub’s transmission port. This delay depends on the total number of connections used for reception and data sizes used in the tag data links. In addition, this delay depends on the switching hub maker and model, but the delay can be approximated with the following table. (For a precise estimate, contact the switching hub manufacturer.)

The following values are the delays when cascade connections are not being used. If cascade connections are used, more nodes can be connected, but the switching hub delays will increase.

Words per connection

Number of connections used for reception

 

 

 

 

 

 

 

16

32

64

128

256

 

 

 

 

 

 

2 words

0.2 ms

0.3 ms

0.5 ms

1.0 ms

1.9 ms

 

 

 

 

 

 

200 words

0.7 ms

1.3 ms

2.5 ms

5.0 ms

10.0 ms

 

 

 

 

 

 

400 words

1.2 ms

2.3 ms

4.6 ms

9.1 ms

18.2 ms

 

 

 

 

 

 

600 words

1.7 ms

3.3 ms

6.6 ms

13.2 ms

26.4 ms

 

 

 

 

 

 

722 words

2.0 ms

4.0 ms

7.9 ms

15.7 ms

31.4 ms

 

 

 

 

 

 

The receive processing delay is the delay that occurs within the EtherNet/IP Unit or built-inEtherNet/IP port from the reception of the data packet at the Unit until the completion of reception processing in the Unit. This delay depends on the size of the connections used in the tag data links and the number of connections. In practice, the delay depends on the number of connections used in tag data links with less than 200 words. If the number of connections is “n”, the maximum delay can be calculated with the following equation.

Maximum reception processing delay = 1 + (n × 0.043) ms

The size of the connections may cause a delay when the data sizes are smaller and a large number of packets may be received in a fixed interval, because the data may wait for receive processing.

This example shows how to calculate the tag data link delay when the following tag data link connection settings have been made.

In this case, 17 EtherNet/IP Units or built-inEtherNet/IP ports are being used, and one Unit is receiving 200 words of data from each of the other Units at a packet interval (RPI) of 5 ms. Thus, 16 tag data link connections are used. The length of the cables between the Units is 50 m for all connections.

Send processing delay = 5 ms × (15 − 5/100)% = 0.7475 ms Cable delay = 545 ns × 50 m/100 = 272.5 ns

Switching hub delay = 0.7 ms

Receive processing delay = 1 + (16 × 0.043) ms = 1.688 ms

Tag data link delay = 0.7475 ms + 0.0002725 ms + 0.7 ms + 1.688 ms ≈ 3.14 ms

266

Communications System

Section 10-1

PLC #1

PLC #2

PLC #3

PLC #17

 

5 ms

#2

200 words

#3

5 ms

200 words

200 words

 

× 16

 

#17

5 ms

200 words

267

Adjusting the Communications Load

Section 10-2

10-2Adjusting the Communications Load

In an Ethernet network using a switching hub, the network bandwidth is not shared by all of the nodes; independent transmission paths are established between individual nodes through the switching hub.

A dedicated communications buffer is established in the switching hub for communications between the nodes and full-duplexcommunications (simultaneous transmission and reception) are performed asynchronously with other transmission paths. The communications load in other transmission paths does not affect communications, so packet collisions do not occur and stable,high-speedcommunications can be performed.

The switching hub functions shown in the following table determine the performance of tag data links.

Item

Description

 

 

Buffer capacity

This is the amount of data that can be buffered when packets

 

accumulate at the switching hub.

 

 

Multicast filtering

This function transfers multicast packets to specific nodes

 

only.

 

 

QoS function

This function performs priority control on packet transfers.

 

 

The following table shows the tag data link settings that can be made for individual EtherNet/IP Units as well as the setting ranges.

Item

Contents

Settings

 

 

 

Network bandwidth

Physical Ethernet baud rate

100 Mbps or 10 Mbps

 

 

 

Allowed tag data link

Maximum number of tag data

CJ2M: 3,000 pps max.

communications band-

link packets that can be pro-

Other CPU Units: 6,000

width

cessed in 1 second (pps: pack-

pps max.

 

ets per second)

 

 

 

 

Connection resources

Number of connections that can

CJ2M: 32 max.

 

be established

Other CPU Units:

 

 

256 max.

 

 

 

Packet interval

Refresh cycle for tag data

CJ2M: 1 to 1,000 ms

(RPI: Requested Packet

 

Other CPU Units:

Interval)

 

0.5 to 10,000 ms

 

 

(in 0.5 ms units)

 

 

 

When the tag data link settings exceed the capabilities of the switching hub being used, increase the RPI value. Particularly when using a switching hub that does not support multicast filtering, the settings must be made considering that multicast packets will be sent even to nodes without connection settings.

In addition, if the required tag data link performance cannot be achieved with the switching hub’s capabilities, reevaluate the overall network configuration and correct it by taking steps such as selecting a different switching hub or splitting the network.

The following sections show how to check the device bandwidth being used by the tag data links in the designed network, and how to set the appropriate values.

Note If the Network Configurator is used to set the connection type in the connection settings to a multicast connection, multicast packets will be used. If the connection type is set to apoint-to-pointconnection, multicast packets will not be used.

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Adjusting the Communications Load

Section 10-2

10-2-1Checking Bandwidth Usage for Tag Data Links

The Network Configurator can display the bandwidth actually used for tag data links at each EtherNet/IP Unit, based on the connections set in the network configuration.

The device bandwidth used by tag data links can be checked by clicking the Detail Button in the Usage of Device Bandwidth Area at the bottom of the Network Configuration Window.

Item

Description

 

 

#

The IP address of the device.

 

 

Comment

A description of the device. The comment is displayed below

 

the device icon. The model number of the device is displayed

 

by default.

 

 

Usage of Capacity

The percentage of the allowable communications bandwidth

 

used for tag data links for the device is displayed.

 

Bandwidth used Allowable tag data link bandwidth

 

The values outside parentheses are for when multicast filtering

 

is used.

 

The values inside parentheses are for when multicast filtering

 

is not used.

 

 

Mbit/s

The bandwidth used for communications by the device of the

 

100-Mbpsnetwork bandwidth is shown.

 

The values outside parentheses are for when multicast filtering

 

is used.

 

The values inside parentheses are for when multicast filtering

 

is not used.

 

 

Usage of IP Multi-

The number of multicast IP addresses actually used for com-

cast Addresses

munications by the device is shown.

 

 

269

Adjusting the Communications Load

Section 10-2

 

 

 

 

Item

Description

 

 

 

 

Total usage of IP

The number of multicast IP addresses used in the entire net-

 

multicast addresses

work is shown. This value is used to estimate the number of

 

 

multicast filters for switching.

 

 

 

 

Network Total of

The total network bandwidth used for tag data link communica-

 

Max. Mbit/s

tions in the entire network is shown. Tag data links will not

 

 

operate normally if 100 Mbps is exceeded for the network

 

 

bandwidth.

 

 

 

Checking the Usage of Capacity and Network Bandwidth for Tag Data Links

Checking the Total

Number of Multicast IP

Addresses in the Network

Checking the Total

Maximum Network

Bandwidth

The percentage of the allowable communications bandwidth for tag data links for each EtherNet/IP Unit is displayed as the Usage of Capacity and the bandwidth used for tag data link communications in the entire network is displayed as theMbit/s.

The usage of capacity and used network bandwidth that are displayed in parentheses are for a switching hub that does not use multicast filtering. In this case, multicast packets will be sent to even the nodes without connection settings, so the displayed values will include these packets as well.

These values can be adjusted according to instructions in 10-2-4 Changing the RPI.

When using a switching hub that provides multicast filtering, there must be enough multicast filters for the network being used. The number of multicast IP address used in the entire network that is displayed by the Network Configurator as the Network Total of Max. Mbit/s is based on connection settings.

Make sure that the number of multicast IP addresses used in the entire network does not exceed the number of multicast filters supported by the switching hub. If necessary, change to a switching hub with enough multicast filters, or adjust the usage of capacity and network bandwidth for tag data links (Mbit/ s) values given for a switching hub without multicast filtering (i.e., the values in parentheses). Adjust these values according to instructions in10-2-4 Changing the RPI.

The Network Configurator displays the total maximum bandwidth that can be used for the entire network as the Network Total of Max. Mbit/s. This value indicates the maximum bandwidth that can be used on the transmission paths when switching hubs are cascaded. If the value exceeds the bandwidth of a cascade connection in the actual network, the maximum bandwidth for part of the communications path may be exceeded, depending on how the network is wired.

If this occurs, either calculate the bandwidth usage for each communications path and be sure that the maximum bandwidth is not exceeded for any cascade connection, or adjust the bandwidth for all cascade connections so that the total maximum network bandwidth is not exceeded. Adjust the bandwidth according to instructions in 10-2-4 Changing the RPI.

10-2-2Tag Data Link Bandwidth Usage and RPI

The usage of capacity can be adjusted using the RPI setting. If the RPI is made shorter, the usage of capacity will increase. If the RPI is made longer, the usage of capacity will decrease.

The RPI can be set in any one of the following ways.

Setting the same interval for all connections

Setting a particular device’s connection

Setting a particular connection

When the same RPI is set for all connections, the usage of capacity will basically increase proportionally as the RPI is made shorter.

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Adjusting the Communications Load

Section 10-2

Example:

If the RPI is set to 50 ms for all connections and the usage of capacity is 40%, the usage of capacity may increase to 80% when the RPI is reduced to 25 ms for all connections.

Note Performing message communications or other network operations from the Network Configurator (such as monitoring or other operations that place a load on the network) or from the user application when the tag data link bandwidth usage of capacity is between 80% and 100% can create an excessive load on the network and result in timeouts. If timeouts occur, increase one or all of the RPI settings or reduce the usage of capacity.

10-2-3Adjusting Device Bandwidth Usage

Switching Hubs without Multicast Filtering (100Mbps Hubs)

Switching Hubs with Multicast Filtering (100Mbps Hubs)

Is the network bandwidth without multicast filtering usage under 100 Mbps for each node? (This appears as “Mbit/s” in the dialog box shown on page 269.)

If any node exceeds 100 Mbps, change the connections settings, such as the RPI.

Is the usage of capacity without multicast filtering under 100% for each node? (This appears as “Usage of Capacity” in the dialog box shown on page 269.)

If any node exceeds 100%, change the connections settings, such as the RPI.

Is the total network bandwidth usage under 100 Mbps? (This appears as “Network Total of Max. Mbit/s” in the dialog box shown on page 269.)

If the total bandwidth usage exceeds 100 Mbps, the bandwidth of part of the transmission path (e.g., a switching hub or media converter) had been exceeded as the result of how the network was wired (e.g., switch hub or cascade connection), causing a tag data link to operate abnormally. Check the bandwidth of the transmission path for all cascade connections. If the bandwidth is exceeded, rewire the network or increase the bandwidth between switching hubs (e.g., to 1 Gbps). If these countermeasures are not possible, change the connection settings, e.g., the RPI settings, and adjust the bandwidth for all cascade connections until the total network bandwidth is not exceeded.

Is the network bandwidth usage under 100 Mbps for each node?

If any node exceeds 100 Mbps, change the connections settings, such as the RPI.

Is the usage of capacity under 100% for each node?

If any node exceeds 100%, change the connections settings, such as the RPI.

Is the total network bandwidth usage under 100 Mbps? (This appears as “Network Total of Max. Mbit/s” in the dialog box shown on page 269.)

If the total bandwidth usage exceeds 100 Mbps, the bandwidth of part of the transmission path (e.g., a switching hub or media converter) had been exceeded as the result of how the network was wired (e.g., switch hub or cascade connection), causing a tag data link to operate abnormally. Check the bandwidth of the transmission path for all cascade connections. If the bandwidth is exceeded, rewire the network or increase the bandwidth between switching hubs (e.g., to 1 Gbps). If these countermeasures are not possible, change the connection settings, e.g., the RPI settings, and adjust the bandwidth for all cascade connections until the total network bandwidth is not exceeded.

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Section 10-2

Is the network bandwidth usage without multicast filtering under 100 Mbps for each node or the usage of capacity without multicast filtering under 100% for each node? (These appear as “Mbit/s” and “Usage of Capacity” in the dialog box shown on page 269.)

→ If the total bandwidth usage exceeds 100 Mbps, the bandwidth of part of the transmission path (e.g., a switching hub or media converter) had been exceeded as the result of how the network was wired (e.g., switch hub or cascade connection), causing a tag data link to operate abnormally. Check the bandwidth of the transmission path for all cascade connections. If the bandwidth is exceeded, rewire the network or increase the bandwidth between switching hubs (e.g., to 1 Gbps). If these countermeasures are not possible, change the connection settings, e.g., the RPI settings, and adjust the bandwidth for all cascade connections until the total network bandwidth is not exceeded.

10-2-4Changing the RPI

You can check the usage of capacity offline without multicast filtering against the tag data link's allowable bandwidth by following the procedures in 10-2-1 Checking Bandwidth Usage for Tag Data Links. The usage of capacity without multicast filtering can be adjusted against the tag data link's allowable bandwidth by changing the packet interval (RPI). If the required communications performance cannot be achieved by changing the settings, reevaluate the network starting with the network configuration.

1,2,3... 1. Make the required settings in the Network Configurator’s Network Configuration Window.

2.Click the Detail Button in the Usage of Device Bandwidth Area at the bottom of the Network Configuration Window.

The Usage of Device Bandwidth Dialog Box will be displayed.

272

Adjusting the Communications Load

Section 10-2

The Usage of Capacity column will show the percentage of the allowed tag data link bandwidth being used, and theMbit/s column will show the network bandwidth being used.

3.The usage of capacity can be adjusted by changing the associated devices’ RPI settings.

The RPI settings can be changed with the following three methods.

Method 1: Same Packet Interval Set for all Connections

The usage of capacity can be adjusted by changing the RPI for all of the connections at the same time.

a.Click the Set Packet Interval (RPI) Button at the bottom of the Usage of Device Bandwidth Dialog Box.

b.The Set Packet Interval (RPI) Dialog Box will be displayed. Input a new RPI value, and click the OK Button.

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Adjusting the Communications Load

Section 10-2

Method 2: Changing a Particular Device’s RPI Setting

The usage of capacity can be adjusted for only a particular device by changing the packet intervals (RPI) for all of the device’s connections together. In this case, the usage of capacity will also change for the devices that are the target devices of the connection which was adjusted.

a.Click the Set Packet Interval (RPI) Button at the bottom of the Usage of Device Bandwidth Dialog Box.

b.The Set Packet Interval (RPI) Dialog Box will be displayed. In the Target Device Area, deselect the target devices that are not being adjusted by removing the check marks.

c.Input a new RPI value, and click the OK Button.

Method 3: Changing a Particular Connection’s RPI Setting

The usage of capacity can be adjusted by individually changing the packet intervals (RPI) setting for a particular connection. In this case, the usage of capacity will also change for the device that is the target device of the connection which was adjusted.

274