I/O Scanner Concepts
Original instructions
About us
Introduction
The I/O Scanner is a feature that resides in Ethernet (NOE 771 00, -01, -11, and CPU 651 x0) modules. The I/O Scanner allows, through a controller, repeated reading from and/or writing to scanned devices.
Use the I/O scanner to transfer data between network devices.
Configure the I/O Scanner with Schneider Electric’s programming package Control Expert. (I/O Scanner configuration information appears elsewhere in this guide.)
NOTE: We recommend you program with words if your project involves both 140 CPU 651  x0 modules and 140 NOE 771 01 modules in the same application. Due to the unique manner in which each of these modules were developed, they both correctly scan towards %I, but they interpret the data in different programming languages. The NOE module reads in IEC format; whereas, the controller module reads in LL984 format.
Health Block Bits
Each bit corresponds to an entry in the I/O Scanner table. Each entry in the table represents one logical device.
The bits contain the health status for the Modicon Quantum I/O Scanner.
NOTE: A Quantum PLC does not update health bits in STOP mode.
Device Control Block
With the Device Control Block, disable an individual entry/device in the I/O Scanner table by checking the box and setting the associated bit in Device Control Block to 1.
Repetitive Rate Step
In the Repetitive Rate Step field, 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.
I/O Scan List
The I/O scan list is a configuration table that identifies the targets to which repetitive communications are authorized. While the controller is running, the Ethernet module transfers data to and from the controller’s registers as indicated by the I/O scan list.
I/O Scanner Parameters
The I/O Scanner parameters are described in the following table:
Parameter
Value
Max. No. of Devices
64: 140 NOE 771 00 (Version 2.2 or earlier)
128: 140 NOE 771 00 (Version 3.0 or later), 140 NOE 771 01, and 140 NOE 771 11 only
128: 140 CPU 651 x0
Max. No. of Input Words
4000
Max. No. of Output Words
4000
Health Timeout Value
User configured: 1...65535 ms in 1 ms increments
Last Value (Input)
User configured (Zero or Hold)
IP Address
User configured
IP address of scanned device (Slave IP)
Local and Remote Register Reference
User configured
Repetitive Rate
The rate at which data will be scanned, from 0...65535 in multiples of:
  • If you are running Unity Pro V2.0 or higher
    • 140 NOE 771 01/11: 16 ms
    • 140 CPU 651 x0: 10 ms
  • If you are running Unity Pro V4.0
    • 140 NOE 771 01/11: 5 ms (min), 200 ms (max)
    • 140 CPU 651 x0: 5 ms
Unit ID
User configured
Configure ID only if using a bridge
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).
  • Deselect the check box to disable this feature (default). Defines a new bit, and sets it to zero (0).
Operation through a bridge
Modbus bridge: Supported
Modbus Plus bridge: Supported
Elsewhere in this guide is information about I/O scan response times for high-performance communications modules.
Using the I/O Scanner with an IP Router
NOTE: The I/O Scanners in the 140 NOE 771 x1 and 140 CPU 651 x0 modules send out requests with a Time To Live (TTL) of 32, which allows passage through multiple routers.
Device Control Block
Important information about using the Device Control Block:
Registers
The Device Control Block consists of registers either 8 single words or 4 double words. Contents of the registers are mapped in the controller’s memory. Each bit corresponds to an entry in the table (see the tables below.)
Disabling Devices
Each I/O Scanner device can be disabled. To disable individual devices:
  1. Select the Device Control Block option on the I/O Scanner tab in Control Expert. (Insert a check mark in the box.)
  2. Set the associated bit = 1.
Mapping Device Control Block Bits to I/O Scanner Entry Numbers (#)
See the table for mapping entry numbers to bits.
Each entry number represents a logical device on the network.
Setting Bits
If Device Control Block bit is set to
  • 0 = Device is enabled
  • 1 = Device is disabled
Mapping Device Control Block Bits to I/O Scanner Entry Numbers (#)
Single Word (W) Register (%MDx:4)
W1 %MW [x+1]
Table Entry #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
W2 %MW [x+2]
Table Entry #
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
W3 %MW [x+3]
Table Entry #
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Word 4 through Word 7 (Table Entry 49 through 112)
W8 %MW [x+8]
Table Entry #
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
NOTE: Bits are counted from right to left starting from bit 0 (low bit). Examples: to configure %MD1:4 as a device control block in the I/O Scanner table, use %MW2, bit 15 to enable or disable table entry 1. Use %MW3, bit 15 to enable or disable table entry 17.
NOTE: Quantum and Premium co-processors follow Premium Ethernet module control bit operation.
Double Word (DW) Register (%MDx:4)
DW1%MD x[0]
Table Entry #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
DW2 %MD x[1]
Table Entry #
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Table Entry #
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Word 3 through Word 4 (Table Entry 49 through 112)
DW %MD x[4]
Table Entry #
113
114
115
116
117
118
119
120
12
122
123
124
125
126
127
128
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
NOTE: Bits are counted from right to left starting from bit 0 (low bit). For example, to configure %MD1:4 as a device control block in the I/O scanner table, use %MD1[0], bit 31 to enable or disable table entry 1. Use %MD1[1], bit 15 to enable or disable table entry 17.