Datalogic GWY-01-PBS-01, Reference Manual

Page: 73 / 101

PROFIBUS INTERFACE
65
5
The Slave writes the first fragment of the response into the Input Buffe r, and toggles Bit 0 of
the IBCB to indicate that there is a response fragment ready for the master, and sets Bit 3 of
the IBCB to 1 to indicate that this is a fragment of a longer response (i.e. there is more data
remaining) The Slave also simultaneously makes the same changes to the IBDCB .
NOTE
Bit 3 is not a toggle – If it is 1, then there are more fragments to follow. If it is
0, it is either a complete response, or the final fragment of a response.
(See the
Green changes below)
Output Buffer Input Buffer
Byte # Value Byte # Value
00:
82 Output Buffer Control Byte
(OBCB)
7 6 5 4 3 2 1 0
[1] [0] [0] [0] [0] [0] [1] [0]
00
8B
Input Buffer Control Byte
(IBCB)
7 6 5 4 3 2 1 0
[1] [0] [0] [0] [1] [0] [1] [1]
01: 00 (Always 0) 01: 00 (Always 0)
02: 0C (Packet length in bytes) 02: 1C (Packet length in bytes)
03:
04:
05:
06:
07:
08:
09:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
..
30: 00
06
AA
05
00
01
03
E8
00
00
00
32
00
00
00
00
00
00
..
00 (CBx Command word length MSB)
(CBx Command word length LSB)
Minimum of 6 words
(CBx Command Type) Always AA
(CBx Command Opcode)
0x05 = Read Tag Data
(CBx Command, byte not used)
(CBx Command “Node ID”)
(CBx Command Timeout MSB)
(CBx Command Timeout LSB)
0xE8 = 1000 ms timeout
(CBx Command Start Address MSB)
(CBx Command Start Address LSB)
address 0
(CBx Command Length MSB)
(CBx Command Length LSB)
50 bytes 03:
04:
05:
06:
07:
08:
09:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
00
1F
AA
05
00
01
01
01
00
01
1D
32
2F
13
19
45
94
D1
B5
FA
C7
42
33
58
A3
55
88
49
(CBx Response word length MSB)
(CBx Response word length LSB)
Minimum of 6 words
(CBx Response Type)
AA=Normal Response
(CBx Response Opcode)
05=Continuous Read Response
(CBx Response Instance Counter)
(CBx Response “Node ID”)
(CBx Response Timestamp Month)
(CBx Response Timestamp Day)
(CBx Response Timestamp Hour)
(CBx Response Timestamp Minute)
(CBx Response Timestamp Second)
(CBx Response “Data length”)
50 bytes (total Tag Data)
(CBx Response Data Byte 1)
(CBx Response Data Byte 2)
(CBx Response Data Byte 3)
(CBx Response Data Byte 4)
(CBx Response Data Byte 5)
(CBx Response Data Byte 6)
(CBx Response Data Byte 7)
(CBx Response Data Byte 8)
(CBx Response Data Byte 9)
(CBx Response Data Byte 10)
(CBx Response Data Byte 11)
(CBx Response Data Byte 12)
(CBx Response Data Byte 13)
(CBx Response Data Byte 14)
(CBx Response Data Byte 15)
(CBx Response Data Byte 16)
31: 82
Data Consistency Byte (OBDCB)
31:
8B Data Consistency Byte (IBDCB)
The Master can see that
Bit 3 of the IBCB & IBDCB has been set to 1, so it knows that the
response in the Input Buffer is just a fragment of a longer response, and not a complete
response, and that there are more fragments to follow.