Configuring the I/O Scanning Service
Original instructions
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Introduction
The Modicon 140 NOE 771 01 module supports Ethernet communication services such as I/O scanning, Global Data, Modbus messaging, SNMP, etc. This example shows you how to configure the I/O scanning service. This service is used to:
Selecting the I/O Scanning Parameters
Perform the following steps to setup the I/O scanning parameters:
Step
Action
1
Open the Control Expert program on your PC.
2
In the Project Browser, locate the Communication → Networks sub-directory.
3
Click the network name (140 NOE 771 01 in our example) to open the module configuration table.
4
In the Module Utilities dialog, select Yes in the I/O Scanning field:
5
Click the I/O Scanning tab to display the I/O scanning configuration screen:
6
Type in the parameter settings under each of the column headings for the I/O Scanner Configuration. Refer to the parameter definitions below.
7
Click the validate check box in the upper tool bar to confirm the I/O scanning parameter settings.
Health Block
The Health Block (number 1 in previous figure) lets you define the first word or bit in a health table. That table can be up to 8 words (%IW) or 128 bits (%I) in length. Each bit in the table represents the status of an individual device. The table below shows how the bits are displayed based on the data type you use.
Bit
Data Type
%I
%IW
1
%I1
%IW1.0
2
%I 2
%IW1.1
...
16
%I16
%IW1.15
17
%I17
%IW2.0
By default, the table comprises words starting at %IW1.0. If you want to set the table to bits, you need to specify a %I value in an increment of 16 (%I1, %I16, %I32, etc.).
NOTE: The Health Block is available only for the NOE 771 00, -01, and -11. It is not available for the CPU 651 x0.
NOTE: For Safety Monitor applications, the Health Block is mapped on %M/%MW from the UMA zone instead of %I/%IW.
Device Control Block
The Device Control Block (number 2 in previous figure) lets you disable any scanned device by setting a bit associated with that device to 1. The I/O scanner closes the connection and sets the Health Bit to 0 (unhealthy state).
To enable the Device Control Block select the check box in the I/O Scanner configuration dialog (number 2 in previous figure).
NOTE:
To enable the Device Control Block, use:
  • Unity Pro at V2.0 or later
  • a 140 NOE 771 01 or 140 NOE 771 11at version 3.5 or later
  • a 140 CPU 651 x0 at version 2.0 or later
If you attempt to enable the Device Control Block with an earlier version of the firmware, the I/O scanning service is disabled.
If the check box is not selected, the I/O scanner service is enabled, and you cannot disable the I/O scanning of individual devices.
Disabling I/O scanning with the Device Control Block is equivalent to ending communication between the scanner and the device. Therefore:
  • The fallback positions are applied to the inputs by the scanner.
  • Communication with the device stops.
  • All entries in the IN and OUT tables transfer between the CPU and the scanner on each scan.
As a consequence of the last point above, if you modify a %MWi attached to an input, this %MWi is overwritten by the values coming from the I/O scanner in the next scan (with either 0 or the last input value).
It is possible (but meaningless) to access %MW attached to the outputs because they are not transmitted to the device.
Repetitive Rate Step
The Repetitive Rate Step (number 3 in previous figure) is set in multiples of 5 ms (the minimum) through 200 ms (the maximum).
The Repetitive Rate column is where you enter a rate of time for how often you want the I/O scanner to send a query to the device after the rate has timed out.
NOTE: The repetitive rate of the I/O scanner table is a multiple of the rate displayed in the Repetitive Rate Step. The real repetitive rate being executed by the I/O scanner service is shown in the Repetitive Rate column.
Note: An entry in the Repetitive Rate column is rounded up to the next multiple that was entered in the Repetitive Rate Step if the entry is not a multiple of the Repetitive Rate Step.
For example, if the entry in the Repetitive Rate Step is 5 and you enter a 7 in the Repetitive Rate column, the 7 is rounded up to 10; if you change the Repetitive Rate Step to 6 and enter a 7 in the Repetitive Rate column, the 7 is rounded up to 12.
I/O Scanner Table Parameters
The I/O Scanner parameters are described in the table below:
Parameter
Description
Example
Entry #
This is the first column; it has no name.
Valid range: 1 ... 128
Each entry represents an I/O Scanning exchange on the network.
IP address
This is the IP address of the scanned Ethernet slave device.
192.168.1.100
Device Name
To configure a device (Advantys island or DTM), click the ... button to open the Property box to start the device configuration software.
For an introduction to this procedure for Advantys, go here.
For an introduction to this procedure for DTMs, go FDT Container.
NOTE: While the Property box is open, Property cannot be edited.
MySTB1 or Master_PRM_DTM_10
Unit ID
This field associates the slave address of the device connected to an Ethernet/Modbus gateway with the IP address of that gateway:
  • Value range: 1 to 255
  • Default value: 255
NOTE:
  • When using a bridge, enter the bridge index (1 to 255) in this field.
  • If you are copying the I/O scanning configuration from a 140 NOE 771 •• to a 140 NOC 771 ••, set the Unit ID to a value from 1 to 254.
255
Slave Syntax
Use this drop-down menu to pick the way RD Ref Slave and WR Ref Slave values are displayed. There are 4 types of display available:
  • Index: 100
  • Modbus: 400101
    • (Modbus register)
  • IEC 0: %MW100
    • M340 and Premium PLC slaves
  • IEC 1: %MW101
    • Quantum PLC slaves
Index (default value)
Health Timeout (ms)
This field sets the maximum interval between the responses from a remote device. After this time period expires, the received data is invalid. The Health Timeout must be longer than the Repetitive Rate time (ms). For a Quantum 140 NOE771 01 Ethernet module, it also should be longer than the CPU scan time.
For the Health Timeout:
  • Range: 1 ms to 50 s
  • Interval: 1 ms
1500 ms
Repetitive Rate (ms)
The rate at which data is scanned, in multiples of 16 ms.
64 ms
RD Master Object*
Destination address in the master PLC where, from each device, newly read information is stored
%MW10
RD Slave Ref.**
Source address index in the slave/remote device
The format of this value depends on the Slave Syntax:
  • Index: 5
  • Modbus: 400006
  • IEC 0: %MW5
  • IEC 1: %MW6
RD length
Number of words to read
10
Using these examples, Master Object 140 NOE 771 01 reads data from address 192.168.1.100 starting at index 5. It puts the data into the NOE address starting at %MW10 using a read size of 10 words.
Last value (Input)
This field configures the behavior of inputs in the event of an access error in relation to the remote device (for example: inoperative network or device power supply, etc.):
  • Set to 0: fall back to 0
  • Hold last: maintain last value
Hold last
NOTE: When you select hold last in a 140 CPU 651 •0 coprocessor, the input data may fall back to 0 when the I/O scanner health bits are NOT OKAY. Confirm that the I/O scanner health bits are valid (OK=1) before removing the Ethernet cable to maintain hold last value.
WR Master Object*
Source address of the master PLC whose data is being written into the slave/remote device.
Write operations are always performed at the word level.
%MW20
WR Slave Ref.**
The address of the first word written into the slave/remote device.
The format of this value depends on the Slave Syntax:
  • Index: 100
  • Modbus: 400101
  • IEC 0: %MW100
  • IEC 1: %MW101
WR length
Number of words to be written
1
Using these examples, Master Object 140 NOE 771 01 writes data from address %MW20 to slave address 192.168.1.100 starting at index 100. It puts the data into the NOE address starting at %MW5 using a write size of 1 word.
Gateway/Bridge Device
To allow slower TCP/IP network devices (i.e., gateways and bridges) to be compatible with the I/O Scanner:
  • Select the check box to enable this feature. Defines a new bit, and sets it to high (1).
  • De-select the check box to disable this feature (default). Defines a new bit, and sets it to zero (0).
Description
Additional information
*Master refers to the client PLC that makes the request.
**Slave refers to the server from which data is read or to which data is written.
NOTE: For more information, refer to the Contextual Menu for Copy/Cut/Paste topic.
NOTE: For more information, refer to the I/O Scanning with Multiple Lines topic.