Rockwell Automation 1395 Node Adapter Board - Manual (Page 30)

Chapter 3
Functional Description
3-18
The message returned from the Node Adapter in this example is basically
the same as the header portion of the message sent from the PLC
Controller using the BTW block, except that the message length in Word 4
is different. The Class and Element in Word 3 are returned to the PLC
Controller as they were received in the Node Adapter. If a block transfer
error had occurred, then the ER bit in the BTR block would be set. This bit
corresponds to bit 12 of the first word in the bit array, which in this
example is N111:45/12 for the BTR block. In addition to the error bit, the
high byte of Word 4 contains a status code, defined in Table 3.B. If there
are no block transfer errors occurring, then the high byte of Word 4 is 0.
Block Transfer Read Data Available Example
A block transfer read data available request is performed using the same
rung as for the write request. The only difference is in the data contained in
the data file. Using the same parameter as in the block transfer write
example, the data file will appear as shown below:
00
Value of Parameter
00 00 00 02 02 00 0C 02 71 00 00
N111 : 5
Word 1
N111 : 6
Word 2
N111 : 7
Word 3
N111 : 8
Word 4
N111 : 9
Word 5
N111 : 10
Word 6
Parameter Number
Length in Bytes
Status Byte
Class (Read Data)
Element (Parameter)
Once the message has been processed, the Node Adapter will return the
requested data to the data file associated with the BTR block as shown
below:
00
Value of Parameter
00 00 00 02 02 00 0C 02 71 00 02
N111 : 50
Word 1
N111 : 51
Word 2
N111 : 52
Word 3
N111 : 53
Word 4
N111 : 54
Word 5
N111 : 55
Word 6
Parameter Number
Length in Bytes
Status Byte
Class (Read Data)
Element (Parameter)