Allen-Bradley SLC 500 DeviceNet, Руководство пользователя, Страница: 103 / 139

Publication 1747-6.5.5 - August 2000
Data Map Example A-3
The status and data bits for each scanned device are mapped to the scanner’s
discrete input data table. Data bits are mapped in the first four words while
status bits are mapped in the next four words of the table. The bit numbering
for device data bits begins with 0. This numbering starts over in word 5 for
device status bits. This feature makes it possible to directly correlate a
device’s MAC ID with the placement of its bits in the data table. For example,
the data bit for node #11 is mapped to bit 11, word 1 in the data table. Its
status bit is mapped to bit 11, word 5 of the data table.
The processor reads the scanner’s data table to transfer its contents to the SLC
processor input image table.
In this example, nothing is mapped to the DeviceNet input
data area of the processor’s M1 file. All input data is mapped
to the processor’s input image table via the scanner’s discrete
input data table.
DeviceNet Message
from Node #11
1 byte
S
D
1747-SDN Scanner Discrete
Input Data Table
15
31
47
63
11 0
16
32
48
word 1
word 2
word 3
word 4
15 0 word 0
15
31
47
63
11 0
16
32
48
word 1
word 2
word 3
word 4
bit number
word 0 Status
words 1-31 DeviceNet Input Data (31 words)
words 0-149 DeviceNet Input Data (150 words)
words 150-210 Reserved (61 words)
word 211 Scan Counter (1 word)
wordS 212-215 Device Active Table (4 words)
words 216-219 Device Failure Table (4 words)
words 220-223 Auto Verify Table (4 words)
words 224-255 Client Server Table (32 words)
SLC Processor M1 File
SLC Processor Input Image Table