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Adjusting the Communications Load

Section 10-2

a.Click the Close Button at the bottom of the Usage of Device Bandwidth Dialog Box.

b.Double-clickthe device that is set as the originator of the desired connection. The Edit Device Parameters Dialog Box will be displayed.

c.In the Register Device List, select the connection for which you want to change the RPI, and click the Edit Button.

d.The device’s Edit Connections Dialog Box will be displayed. Input a new RPI value, and click the OK Button.

275

Adjusting the Communications Load

Section 10-2

4.If the usage of capacity cannot be adjusted to the desired level when the setting described above has been performed, reconsider the network configuration considering the following points. Refer to 10-2-3 Adjusting Device Bandwidth Usage.

Reduce the number of nodes and number of connections.

Split the network.

5.Check the bandwidth usage again.

If the connection settings have been changed, click the Detail Button in the Usage of Device Bandwidth Area at the bottom of the Network Configuration Window and check bandwidth usage according to the instructions in

10-2-1 Checking Bandwidth Usage for Tag Data Links. It is particularly important to check the usage of capacity when an individual connection’s RPI setting was changed without using the Set Packet Interval (RPI) Button at the bottom of the Usage of Device Bandwidth Dialog Box.

6.Run user tests to verify that there are no problems with the new settings.

10-2-5RPI Setting Examples

The following examples explain how to calculate the packet intervals (RPI) in the following network configuration.

276

Adjusting the Communications Load

Section 10-2

Example Conditions

Connections

In this example, there are 10 CS1W-EIP21Units and 10CJ1W-EIP21Units for a total of 20 devices connected in the network. Each device has one 100word tag for transmission and nineteen100-wordtags for reception, so that the Units exchange data mutually.

By default, the packet intervals (RPI) are set to 10 ms for all of the connections. The devices’ IP addresses range from 192.168.250.1 to 192.168.250.20.

IP address:

100 words

100 words

100 words

100 words

192.168.250.1

CS1W-EIP21

Transmit

192.168.250.2

CS1W-EIP21

Transmit

192.168.250.3

CS1W-EIP21

Transmit

192.168.250.20

CJ1W-EIP21

Transmit

Tag data link area with 100 words × 20 Units

Checking the Device

Bandwidth Usage

10 CS1W-EIP21Units + 10CJ1W-EIP21Units = 20 Units total The RPI is 10 ms (ethernet default) for all connections.

When the Detail Button is clicked in the Usage of Device Bandwidth Area, it is apparent that the percentage of the allowed tag data link bandwidth being used by each device’s tag data link (Usage of Capacity) is 39.67%, as shown in the following dialog box.

277

Adjusting the Communications Load

Section 10-2

Changing the

Settings

Method 1: Same Packet Interval Setting for All Connections

The percentage of the allowed tag data link bandwidth being used (Usage of Capacity) was 39.67% with the RPI set to 10.0 ms for all of the connections, so the RPI will be set to 5.0 ms, with a target of 80% or less of the allowable bandwidth.

Click the Set Packet Interval (RPI) Button at the bottom of the Usage of Device Bandwidth Dialog Box. The Set Packet Interval (RPI) Dialog Box will be displayed. Input 5.0 ms as the new RPI value, and click theOK Button.

278

Adjusting the Communications Load

Section 10-2

If the packet interval for all connections has been set to the same setting, the dialog box will show that the usage of capacity for the tag data link's allowable communications bandwidth is 73.00% and the fastest set value is 5.0 ms.

Method 2: Changing the Packet Interval (RPI) of Only Specific Devices

In this example, we want faster tag data links for devices 192.168.250.1 and 192.168.250.10 only. Click the Set Packet Interval (RPI) Button at the bottom of the Usage of Device Bandwidth Dialog Box to display the Set Packet Interval (RPI) Dialog Box.

In the Target Device Area, deselect all devices other than 192.168.250.1 and 192.168.250.10 by removing the corresponding check marks. Input 5.0 ms as the new RPI value, and click the OK Button.

The percentage of the allowed tag data link bandwidth being used (Usage of Capacity) increases to 74.67% for devices 192.168.250.1 and 192.168.250.10, which indicates that the RPI is set to a higher speed for these devices’ connections.

279

Adjusting the Communications Load

Section 10-2

The Usage of Capacity values also indicate that the Usage of Capacity has increased (from 39.67% to 43.00%) for all of the other devices, which connect with devices 192.168.250.1 and 192.168.250.10.

In this case, if there is no multicast filter, the value becomes 106.33%. If there is no multicast filter for a switching hub, communications errors may occur depending on the communications load of the EtherNet/IP Unit or built-inEtherNet/IP Unit port.

280

Adjusting the Communications Load

Section 10-2

Method 3: Changing the Packet Interval (RPI) of Only Specific

Connections

In this example, we want a faster tag data links for just a particular connection of device 192.168.250.1.

Double-clickdevice 192.168.250.1 in the Network Configuration Window.

Information about the connection with device 192.168.250.20 is registered in the Register Device List. Double-clickthis connection to edit the settings.

281

Adjusting the Communications Load

Section 10-2

In the Edit Connection Dialog Box, input 1.0 ms as the new RPI value, and click the OK Button. The tag data link bandwidth being used by device 192.168.250.1 (Usage of Capacity) increases to 54.67%, which indicates that a RPI is set to a higher speed for this device.

In this case, the tag data link bandwidth being used by device 192.168.250.20 (Usage of Capacity) also increases (from 39.67% to 56.33%).

282

I/O Response Time in Tag Data Links

Section 10-3

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

Note This section describes the data processing time for an EtherNet/IP Unit or abuilt-inEtherNet/IP port on aCJ2H-CPU6@-EIPCPU Unit. The data processing time for abuilt-inEtherNet/IP port on theCJ2M-CPU3@CPU Unit is different. For details, refer to10-4 Tag Data Link Performance for CJ2M Built-in EtherNet/IP Ports.

10-3-1Timing of Data Transmissions

The following diagram shows the timing of tag data link transmissions between the EtherNet/IP Unit or CJ2H built-inport and the CPU Unit.

The data transmission is processed during the I/O refresh period. Send data is processed with transmission at regular intervals, and received data is processed together with the send data when new data has been received from other nodes. The following diagram shows the timing of data transmissions.

Data received

 

 

 

 

 

 

 

 

 

 

 

EtherNet/IP

 

EtherNet/IP Unit data

 

 

 

 

Unit processing

 

processing time

 

 

 

 

 

 

 

 

 

 

 

 

 

(Refer to 10-3-2.)

 

 

 

 

 

 

 

 

 

 

 

 

 

CPU Unit processing

 

 

Basic

 

Program

 

Peripheral

Basic

 

 

pro-

 

I/O refreshing

pro-

 

 

 

execution

servicing

 

 

 

cesses

 

 

cesses

Data exchange processing

CPU Unit’s cycle time

If there is an interrupt for data transmission processing, the CPU Unit’s cycle time is extended by that interrupt processing time. Refer to 10-3-2 EtherNet/IP Unit or CJ2H Built-in Port Data Processing Time for details.

10-3-2EtherNet/IP Unit or CJ2HBuilt-inPort Data Processing Time

The following formula approximates the time required for the EtherNet/IP Unit or CJ2H built-inport to process data transmissions with the CPU Unit (i.e., the data processing time).

Approximation of the data processing time for an

EtherNet/IP Unit or CJ2H Built-inPort

(0.0008 × Number of data transmission words) + 1.0 ms

283

I/O Response Time in Tag Data Links

Section 10-3

The maximum number of tag data link words that can be transferred by one EtherNet/IP Unit or CJ2H built-inport is 184,832 words. However, if the number of tag data link words exceeds the number of words that can be exchanged with the CPU Unit at one time, the data will be divided and transferred in multiple data exchanges. The following table shows the number of words that each CPU Unit can exchange at one time.

CPU Unit

Number of words per data transmission

 

 

CS/CJ Series

Output/Send: About 7,405 words max. (If there are more words,

 

the data will be divided.)

 

Input/Receive: About 7,405 words max. (If there are more words,

 

the data will be divided.)

 

Note The total amount of send data and receive data that can be

 

exchanged at one time is about 14,810 words maximum.

 

 

SYSMAC CJ2

Output/send: About 6,432 words max. (If there are more words, the

Series

data will be separated into multiple transmissions.)

 

Input/receive: About 6,432 words max. (If there are more words,

 

the data will be separated into multiple transmissions.)

 

Note The total amount of send data and receive data that can be

 

transferred at one time is about 12,864 words maximum.

The number of data exchanges may double as given in the following table according to the relation with the CPU Unit’s cycle time and the data processing time of the EtherNet/IP Unit or CJ2H built-inport.

Condition

Number of data transmissions

 

 

CPU Unit’s cycle time

Number of data transmissions

> EtherNet/IP Unit or CJ2H built-inport

based on the data size

 

data processing time

 

 

 

CPU Unit’s cycle time

Number of data transmissions × 2

≤ EtherNet/IP Unit or CJ2H built-inport

based on the data size

 

data processing time

 

 

 

Note (1) WithCS/CJ-seriesPLCs, consecutive data area words specified in the tag set will be transferred together if possible. Up to 19 send data blocks can be processed in one data transmission; up to 20 receive data blocks can be processed in one data transmission. If there are more blocks, the data will be divided and transferred in separate data transmissions.

(2)The preceding data processing time approximation is the standard formula when a higher priority processing event does not occur in peripheral servicing. For example, if an instruction such as SEND, RECV, or FAL is executed, the instruction’s processing will have higher priority, so the data processing time may be longer.

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

The CPU Unit’s cycle time is affected when the EtherNet/IP Unit or CJ2H builtin port refreshes tag data and status data with the CPU Unit. This effect depends on the size of the tag data links, and can be approximated with the values in the following table. When there are multiple EtherNet/IP Units or CJ2H built-inports, the effect is cumulative.

284

I/O Response Time in Tag Data Links

Section 10-3

 

 

 

 

CPU Unit

Effect of EtherNet/IP Unit or

Total effect when tag data links are being used

 

 

CJ2H built-inport only

 

 

 

 

 

 

CJ2H

CPU Rack: 0.1 ms

CPU Rack: Value from left column + 0.1 ms + No. of words trans-

 

 

Expansion Rack: 0.13 ms

ferred × 0.33 µs (See note 2.)

 

 

 

Expansion Rack: Value from left column + 0.1 ms + No. of words

 

 

 

transferred × 0.45 µs

 

 

 

 

 

CJ2M

CPU Rack: 0.14 ms

CPU Rack: Value from left column + 0.02 ms + No. of words trans-

 

 

Expansion Rack: 0.16 ms

ferred × 0.78 µs

 

 

 

Expansion Rack: Value from left column + 0.02 ms + No. of words

 

 

 

transferred × 0.92 µs

 

 

 

 

 

CJ1

0.25 ms

0.25 ms + 1.5 ms + (Number of words × 1 µs)

 

 

 

 

 

CJ1M

0.17 ms

0.17 ms + 0.1 ms + (Number of words × 0.7 µs)

 

 

 

 

 

CJ1-H

0.1 ms

0.1 ms + 0.1 ms + (Number of words × 0.7 µs)

 

 

 

 

 

CS1

0.2 ms

0.2 ms + 1.5 ms + (Number of words × 1 µs)

 

 

 

 

 

CS1-H

0.1 ms

0.1 ms + 0.1 ms + (Number of words × 0.7 µs)

 

 

 

 

 

Long-distance

0.2 ms × Coefficient 2

(0.2 ms × Coefficient 2) + 1.5 ms + (Number of words × 1 µs ×

 

Rack

 

Coefficient 3)

 

Note (1) When one of the listed CPU Bus Units is mounted in aCS-seriesLongdistance Rack, the I/O refreshing time is extended by the distance to the Rack in which the Unit is mounted, regardless of the model of the CPU Unit. The following graph shows the coefficients (2 and 3) required to calculate this effect.

Coefficient

Distance to Long-distanceRack (m)

(2)The additional time for CJ2H CPU Units with unit version 1.1 or later will be as follows if high-speedinterrupts are enabled.

0.1ms + Number of words transferred × 0.87 µs

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

When using the tag data link functions of the EtherNet/IP Unit or CJ2H built-inport, there is a time lag between the point when the data link area’s data changes due to an input at a node and the point when the change is output at another node’s data link area. This time lag is called the tag data link

I/O response time.

This example shows how to calculate the minimum and maximum I/O response times in the following configuration for connection 1 opened between node 1 and node 2.

285

I/O Response Time in Tag Data Links

Section 10-3

EtherNet/IP

PLC#1

Node 1

Input switch (external input device)

Input W000.01

PLC#2

PLC#3

Node 2

Node 3

Output relay (external output device)

W000.01 Output

Tag Data Link Table

PLC#1

PLC#2

Connection 1

PLC#3

 

 

 

RPI = 10 ms

 

W000

W000

 

 

RPI = 10 ms

722 words x 16 connections

Outputs

Total: 11,552 words

Inputs

256 words x 16 connections

 

 

 

 

 

RPI = 100 ms

 

 

 

 

 

 

Inputs

 

 

 

 

 

 

 

 

 

Outputs

 

Total: 4,096 words

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The following table gives the items required to find the I/O response time and values used in calculations for this system configuration.

Item

 

Value used in calculation example

 

 

 

 

 

 

 

 

PLC#1

PLC#2

 

 

 

External I/O device delay time

Input device delay:

Output device delay:

 

 

 

1.5 ms

2.0 ms

 

 

 

 

Cable length

 

50 m

 

 

 

 

 

CPU Unit model

 

CJ2H CPU Unit

CJ2H CPU Unit

 

 

 

 

RPI

 

10 msec

---

 

 

 

Number of receive connections

0

32

 

 

 

 

CPU Unit cycle time

 

10 msec

15 msec

 

 

 

 

Total number tag

 

Number of send

11,552

None

data link words

 

words

 

 

 

 

 

 

 

 

 

Number of

None

15,648

 

 

receive words

 

 

 

 

 

 

 

Maximum Tag Data Link I/O Response Time

You can find the maximum I/O response time from the total of (1) to (6) in the following figure.

286

I/O Response Time in Tag Data Links

Section 10-3

: I/O processing: Data exchange

Transmission Output path Input device device PLC #2 PLC #1

 

Tag data link I/O response time

 

(1) Input ON (2) Send data

 

(4) Network transmission delay time

 

 

(6) Output ON

response

processing

(3) RPI

(5) Receive data

time

time

processing time

response time

 

Input

Calcu-

PLC #1 processing

lation

Send data processing time

Cycle time x 2

Tag data link refresh cycle

 

 

Receive data processing time

PLC #2 processing

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Calcu-

 

 

 

 

 

 

 

 

lation

 

 

 

 

Cycle time x 4

Output

(1) Node 1 (PLC #1) Input ON Response Time

This is the delay time for the external input device from when the input occurs until the switch actually turns ON and the time until the input data is stored in the memory area of the CPU Unit for PLC #1. In this system, the input switch delay time is 1.5 ms. Also, one CPU cycle time is required until the data is stored in the memory area of the CPU Unit. Therefore, the input ON response time is 1.5 ms + 10 ms, or 11.5 ms.

(2) Node 1 (PLC #1) Send Data Processing Time

This is the time until memory data in the CPU Unit is transferred to the EtherNet/IP Unit. If the amount of data that can be processed in one data transmission with the CPU Unit is exceeded, data transmission will be performed over multiple cycles of the CPU Unit, and so time is calculated for the number of transmissions times the CPU Unit cycle times. The following table gives the send data processing times and breakdown for node 1 (PLC #1) in this system configuration. Refer to 10-3-2 EtherNet/IP Unit or CJ2H Built-in Port Data Processing Time for details on the calculation formula for each item.

Item

Calculation formula

Time

 

 

 

A CPU Unit cycle time

 

10 m sec

for PLC #1

 

 

 

 

 

B Number of transmis-

Number of data transmission words (11,552

2

sions based on the data

words) ÷ 6,432 words (using a CJ2 CPU

 

size

Unit)

 

C EtherNet/IP Unit data

0.0008 × 6,432 + 1.0 (Maximum number of

6.15 m sec

processing time

transmission words per cycle)

 

287

I/O Response Time in Tag Data Links

Section 10-3

 

 

 

 

 

 

 

Item

Calculation formula

Time

 

 

 

 

 

 

 

D Number of data trans-

A 10 m sec > C 6.15 m sec

2

 

 

missions

To meet the conditions, the number of trans-

 

 

 

 

missions is the same as B.

 

 

 

 

 

 

 

 

Total:

CPU Unit cycle time of A PLC #1 × D Num-

20 m sec

 

 

(2) Send data process-

ber of data transmissions

 

 

 

 

 

 

 

ing time

 

 

 

 

 

 

 

 

(3) Packet Interval (RPI)

This is the communications refresh cycle set for each connection using the Network Configurator. In this system, it is the refresh cycle for connection 1 (10 ms), which includes W000.01.

(4) Network Transmission Delay Time

This is the total of the send processing delay, receive processing delay, switching hub delay, and cable delay. Refer to 10-1-3 Network Transmission Delay Time for details on the calculation formula for network delay time. In this system, it is 5.2 ms.

Delay item

Calculation formula

Max. delay time

 

 

 

A Send processing delay

10 m sec × (15-10msec/100)%

1.49 msec

 

 

 

B Cable delay

545 nsec + 50 m/100

272.5 nsec

 

 

 

C Switching hub delay

2 msec + Approx. 0.7 msec

2.7 msec

 

 

 

D Receive processing

1 + (0 connection × 0.043)

1.0 msec

delay

 

 

 

 

 

Total:

A + B + C + D

5.2 msec

(4) Network Transmission

 

 

Delay Time

 

 

(5) Node 2 (PLC #2) Receive Data Processing Time

This is the time to transfer the data received by the EtherNet/IP Unit or CJ2H built-inport to the memory area in the CPU Unit. Receive data is transferred in the order that it is received, but if the amount of data that can be processed in one transmission is exceeded, multiple cycles are required to transfer the data. Also, data transmission is performed only once per CPU Unit cycle. Therefore, if data transfer has ended in the cycle in which data is received, the start of transmission for received data will be delayed by one CPU Unit cycle time.

In this system configuration, data transfer is performed a maximum of three times based on the data size of node 2 (PLC #2) to transfer received data for node 1 (PLC #1) and node address 3 (PLC #3). Also, the cycle time of PLC #2 is 15 ms, the effect on the CPU Unit cycle time is 2.3 ms, and the data processing time for the EtherNet/IP Unit or CJ2H built-inport is 6.15 ms. The number of data transmissions is thus calculated as 3. In addition, the number of data transmissions is calculated as a maximum of 4 (3 + 1) because it is necessary to consider a delay of one CPU Unit cycle time in transferring received data.

Item

Calculation formula

Time

 

 

 

A CPU Unit cycle time

---

15 msec

 

 

 

B Number of transmis-

Number of data transmission words (15,648

3

sions based on the data

words) ÷ 6,432 words (using a CJ2 CPU

 

size

Unit)

 

 

 

 

C EtherNet/IP Unit data

0.0008 × 6,432 + 1.0 (Maximum number of

6.15 msec

processing time

transmission words per cycle)

 

 

 

 

288

I/O Response Time in Tag Data Links

Section 10-3

 

 

 

 

 

Item

Calculation formula

Time

 

 

 

 

 

D Number of data trans-

A 10 m sec > C 6.15 m sec

4

 

missions

To meet the condition to enable processing

 

 

 

in one data transmission, the number of

 

 

 

transmissions is the same as B plus 1.

 

 

 

(Delay of one CPU Unit cycle time)

 

 

 

 

 

 

Total:

A Cycle time × D Number of data trans-

60 msec

 

(5) Receive data process-

missions

 

 

ing time

 

 

 

 

 

 

(6) Output ON response time

This is the delay time for the external output device from when the output bit turns ON in the memory of the CPU Unit until the output is actually performed. In this system configuration, the delay time for an output relay is 2.0 ms. Also, one CPU cycle time is required until the data is stored in the memory area of the CPU Unit.

Item

Time

 

 

A CPU Unit cycle time of PLC #2

15 msec

 

 

B Output relay delay time

2.0 msec

 

 

Total:

17.0 msec

(6) Node 2 (PLC #2) output ON response time

 

 

 

The maximum tag data link I/O response time for this system configuration found from the total of (1) to (6) is 124 ms.

(1)

Node 1 (PLC #1) input ON response time

11.5 msec

 

 

 

(2)

Node 1 (PLC #1) send data processing time

20 msec

 

 

 

(3)

Packet Interval (RPI)

10 msec

 

 

 

(4)

Network Transmission Delay Time

5.5 msec

 

 

 

(5)

Node 2 (PLC #2) receive data processing time

60 msec

 

 

 

(6)

Output ON response time

17 msec

 

 

Maximum I/O response performance (total of (1) to (6))

124 msec

 

 

 

Note The I/O response time may be longer due to noise, or other events.

289

I/O Response Time in Tag Data Links

Section 10-3

Minimum Tag Data Link I/O Response Time

: I/O processing

: Data exchange

 

Tag data link I/O response time

 

(1) Input ON

 

 

(2) Network

 

transmission delay time

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

response

 

 

(3) Output

ON

 

time

 

 

response time

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Input device

Input

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Calcu-

 

 

 

 

 

 

 

 

 

 

PLC #1 processing

 

 

 

lation

 

 

 

 

 

 

 

 

 

 

PLC #1

 

 

 

 

 

 

 

 

 

 

 

Transmission path

 

 

 

 

 

 

 

 

 

 

Tag data link refresh cycle

 

 

 

 

 

 

 

 

 

 

PLC #2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Calcu-

PLC #2 processing

lation

Output device

 

 

 

 

 

Output

 

 

 

The minimum tag data link I/O response time, which occurs when there are no processing delays, is calculated as follows.

(1)

Node 1

Input switch delay time

1.5 ms

(PLC #1) input ON response time

 

 

CPU Unit cycle time of PLC #1

10.0 ms

 

 

 

 

(2)

Transmission time (722 send data words)

0.121 msec

 

 

 

 

(3)

Node 2

CPU Unit cycle time of PLC #2

15.0 ms

(PLC #1) output ON response time

 

 

Output relay delay time

2.0 ms

 

 

 

 

 

Total (tag data link I/O response time)

28.6 ms

 

 

 

 

When the baud rate is 100 Mbps, the transmission time can be calculated with the following equation. If a network delay does not occur, just this transmission time is added.

Transmission time =

(Number of send data words × 2 + 74) × 8 × 0.00001 ms

Note The I/O response time may be longer due to noise, or other events.

290

Tag Data Link Performance for CJ2M Built-inEtherNet/IP Ports

Section 10-4

10-4Tag Data Link Performance for CJ2MBuilt-inEtherNet/IP Ports

10-4-1Overview

The built-inEtherNet/IP port on a CJ2M CPU Unit(CJ2M-CPU3@)supports tag data links for up to 32 connections, with a data size of 20 words per connection. These specifications are different from those of CJ2Hbuilt-inports and EtherNet/IP Units. The maximum number of words that can be transmitted for tag data links is 640 words. This 640 words is the amount of data that is processed for one data transmissions between the CPU Unit and the CJ2Mbuilt-inport.

The tag data link specifications of CJ2M built-inports are provided in the following table. If these specifications are insufficient for the required system configuration, use a CJ2Hbuilt-inport on aCJ2H-CPU6@-EIPCPU Unit or aCJ1W-EIP21EtherNet/IP Unit.

Tag Data Link Specifications for CJ2M Built-inEtherNet/IP Ports

 

CJ2M built-inport

Reference: CJ2H built-inport

 

(CJ2M-CPU3@)

(CJ2H-CPU6@-EIP)

Number of connections

32

256

 

 

 

Packet interval (RPI)

1 to 10,000 ms (in 0.5-msunits)

0.5 to 10,000 ms (in 0.5-msunits)

 

 

 

Allowed communications

3,000 pps

6,000 pps

bandwidth per Unit (PPS)

 

 

 

 

 

Number of tags that can be

32

256

registered

 

 

 

 

 

Tag types

CIO Area, DM Area, EM Area, Holding Area, Work Area, and network symbols

 

 

 

Number of registrable tag sets

32

256

 

 

 

Number of tags per connec-

8 (7 tags when the tag set contains the PLC status)

tion

 

 

 

 

 

Maximum size of 1 tag set

20 words

722 words

 

(The PLC status uses 1 word when the tag

(The PLC status uses 1 word when the tag

 

set contains the PLC status.)

set contains the PLC status.)

 

 

 

Maximum data size per con-

20 words

722 words

nection

 

 

 

 

 

Maximum link data size per

640 words

184,832 words

node

 

 

 

 

 

Maximum number of tags that

Output/Transmission

Output/Transmission

can be refreshed per CPU Unit

(CPU → EtherNet/IP): 32

(CPU → EtherNet/IP): 256

cycle

Input/Reception (EtherNet/IP → CPU): 32

Input/Reception (EtherNet/IP → CPU): 256

 

 

 

 

Data that can be refreshed per

Output/Transmission (CPU → EtherNet/IP):

Output/Transmission (CPU → EtherNet/IP):

CPU Unit cycle

640 words

6,432 words

 

Input/Reception (EtherNet/IP → CPU):

Input/Reception (EtherNet/IP → CPU):

 

640 words

6,432 words

 

Note The total for output/transmission and

Note The total for output/transmission and

 

input/reception is 640 words.

input/reception is 12,864 words.

Tag Data Link System

Configuration

Example

This example configuration is based on the maximum specifications for CJ2M built-inports where all nodes send and receive data to the other nodes. In this case, the maximum send area for each node in a17-nodeconfiguration is 20 words.

For example, node 1 establishes 16 send connections and 16 receive connections to the other 16 nodes, for a total of 32 connections. The maximum data size per connection is 20 words, so the send area in node 1 is 20 words and the receive areas in node 1 are each 20 words.

291

Tag Data Link Performance for CJ2M Built-inEtherNet/IP Ports

Section 10-4

If the same RPI is set for all connections, 12 ms is the lowest setting that can be used.

Calculation Example

(1,000 ÷ 12 [ms] (RPI) + 1,000 ÷ 100 [ms] (heartbeat transmission period)) × 32 (connections) = 2,987 pps < 3,000 pps

 

Send connections = 16

*All nodes use CJ2M built-inports.

 

(20 words × 16 = 320 words)

 

 

 

Node 1

Node 2

Node 3

Node 16

Node 17

Send 20 words

Receive 20 words

Receive 20 words

Receive 20 words

Receive 20 words

 

Receive 20 words

Send 20 words

Receive 20 words

Receive 20 words

Receive 20 words

Receive 20 words

Receive 20 words

Send 20 words

Receive 20 words

Receive 20 words

 

Receive 20 words

Receive 20 words

Receive 20 words

Send 20 words

Receive 20 words

 

 

 

 

Receive 20 words

Receive 20 words

Receive 20 words

Receive 20 words

Send 20 words

 

 

 

 

Receive connections = 16 (20 words × 16 = 320 words)

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

With tag data links, if the data in the data link area for a node changes due to an input to that node, a certain amount of time is required for the data in data link area at another node to be updated and output.

The I/O response time for tag data links can be calculated for a CJ2M built-inport in the same was as it can for a CJ2Hbuilt-inport (refer to10-2-4 Changing the RPI). Here, formulas to calculate guideline I/O response times are provided. (Tag data link delays are ignored because the data link size handled by thebuilt-inCJ2M port is small.)

Maximum I/O Response Time

Input ON delay + Cycle time of sending PLC × 2 + RPI + Cycle time of receiving PLC × 2 + Output ON delay

Minimum I/O Response Time

Input ON delay + Cycle time of sending PLC + Cycle time of receiving PLC +

Output ON delay

 

PLC #1

 

PLC #2

 

Node 1

Connection

Node 2

 

 

RPI: 12 ms

 

Cycle time: 5 ms

20

 

20

words

 

words

Input ON response time:

 

 

 

1.5 ms

 

 

 

 

 

All connections

 

 

 

EtherNet/IP

 

Input

 

 

Output

Cycle time: 10 ms

Output ON response time: 2.0 ms

Data link

292

Tag Data Link Performance for CJ2M Built-inEtherNet/IP Ports

Section 10-4

For example, the maximum and minimum I/O response times would be as follows for the above system.

Maximum response time:

1.5 ms + 5 ms × 2 + 12 ms + 10 ms × 2 + 2.0 ms = 45.5 ms

Minimum response time:

1.5 ms + 5 ms + 10 ms + 2.0 ms = 18.5 ms

Note If the message service is used at the same time on the CJ2Mbuilt-inport, the tag data link I/O response time will change.

293

Message Service Transmission Delay

Section 10-5

10-5Message Service Transmission Delay

This section explains the maximum transmission delay that can occur between the execution of a SEND(090), RECV(098), or CMND(490) instruction in the ladder program until completion of the instruction. This delay does not include the time required for the tag data link or the execution time of the ladder program itself.

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

Use the following equation to calculate the maximum transmission delay that can occur between the execution of a SEND(090) or RECV(098) instruction in the ladder program until completion of the instruction.

SEND(090) Instruction

Execution of SEND(090) in user program

CPU Bus Unit service cycle (Local node)

CPU Bus Unit service processing time (Local node)

Send processing

Transmission delay

Receive processing

CPU Bus Unit service cycle (Remote node)

CPU Bus Unit service

processing time (Remote node)

CPU data set processing

Maximum transmission delay

CPU Bus Unit Service

Cycle (Local Node)

Maximum transmission delay =

CPU Bus Unit service cycle (local node)

+CPU Bus Unit service processing time (local node)

+Send processing

+Transmission delay

+Receive processing

+CPU Bus Unit service cycle (remote node)

+CPU Bus Unit service processing time (remote node)

The following table shows the service cycle, which depends on the CPU Unit’s CPU processing mode setting.

CPU execution mode

Processing time details

Normal Mode (See note.)

One CPU Unit cycle time

Priority peripheral servicing

 

Parallel processing with syn-

 

chronous memory access

 

Parallel processing with asyn- 0.2 ms + peripheral servicing time (1 ms max. for

chronous memory access

peripheral servicing of each Special I/O Unit, CPU

 

Bus Unit, peripheral port, RS-232Cport, and Inner

 

Board)

Note CJ2 CPU Units support only Normal Mode.

294