Rockwell Automation 1785-Vx0B, D17856.5.9 PLC-5 VME VMEbus Programmable Controllers User Manual - Manual (Page 85)

Chapter 6
PLC-5/VME Processor
Communications Commands
6-16
Array Example
The array includes two ID descriptors, the first specifies the structure as an
array and its total length, the second specifies the type of data in the array
and the number of bytes per element. You must count the second
descriptor as part of the data field.
Important: Select the array structure when transferring multiple elements
of the same data type.
In this example, the first byte is the data-type field and specifies size (total
number of data bytes including second descriptor), the second byte is the
ID descriptor for the array (both bytes in field a), the third byte is the ID
descriptor for the data type followed by data bytes (field b).
This array could include enough bytes to fill a packet.
10010111
Bit 76543210
00001001
01000010
a
ID in next one byte
Size = 7 bytes including second descriptor
value: 0, -2, 255
00000000
00000000
11111110
ID = 9 for array
11111111 (MS)
11111111
ID = integer,
size = 2 bytes per element
Integer 0 (LS)
(MS)
Integer 2 (LS)
Integer 1 (LS)
b
00000000 (MS)
a
b