Atlas Copco PowerMACS 4000, User Manual

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Peripheral Devices
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LEN is the length of the complete package, including both SEQ and LEN . LEN is therefore always equal
to N + 4 where N is the number of data bytes contained in the package.
To reconstruct the Data item being read you just have to concatenate the Data part (Data byte 1, …) of
each package, from first package (
SEQ = 1) to the last package ( SEQ = -K).
Example: Assuming that a complete cycle data consists of the 10-character string "ABCEDFGHIJ"
should be read using an 8-byte buffer then the below data transfer will occur when the cycle
data is requested (all data is written in Hexadecimal notation):
A Cycle data Package returned by the first read request
0
0x41 („A‟)
0 0x00
1
0x42 („B‟)
1 0x01
SEQ = 1
2
0x43 („C‟)
2 0x00
3
0x44 („D‟)
3 0x08
LEN = 8
4
0x45 („E‟)
4
0x41 („A‟) Item data byte 0
5
0x46 („F‟)
5 0x
42 („B‟) Item data byte 1
6
0x47 („G‟)
6
0x43 („C‟) Item data byte 2
7
0x48 („H‟)
7
0x44 („D‟) Item data byte 3
8
0x49 („I‟)
9
0x50 („J‟)
Package returned by the second read request
0 0x00
1 0x02
SEQ = 2
2 0x00
3 0x08
LEN = 8
4
0x45 („E‟) Item data byte 4
5
0x46 („F‟) Item data byte 5
6
0x47 („G‟) Item data byte 6
7
0x48 („H‟) Item data byte 7
Package returned by the third read request
0 0xFF
1 0xFD
SEQ = --3
2 0x00
3 0x06
LEN = 6
4
0x49 („I‟)
Item data byte 8
5
0x50 („J‟) Item data byte 9
6 xx not set
7 xx not set