Balluff BIS M-370-000-A02, Manual, Page: 146 / 198

PROFIBUS INTERFACE
139
9
9.5.2 Example 2: Unsolicited Responses (Continuous Read Mode)
In some modes (such as Continuous Read Mode) the slave can generate unsolicited
responses. If the Slave generates an unsolicited response, it will place the response in the
Input Buffer, as long as the Master has acknowledged receiving the previous response. If the
Master does not perform the handshake to acknowledge the previous response, the
responses will accumulate in the internal memory buffer of the Slave (The RFID processor
unit has an internal
2K buffer for responses) and the responses will remain until the
handshakes are performed for each response.
For this example, the processor unit automatically reads a tag (6 bytes of data), and places
the “response” in the Input Buffer, and toggles
Bit 0 to indicate that a response is waiting.
Although no command was issued by the Master, we will still call this a “response”.
(See the
Green changes below)
Output Buffer Input Buffer
Byte # Value Byte # Value
00:
80 Output Buffer Control Byte
(OBCB)
7 6 5 4 3 2 1 0
[1] [0] [0] [0] [0] [0] [0] [0]
00
81
Input Buffer Control Byte
(IBCB)
7 6 5 4 3 2 1 0
[1] [0] [0] [0] [0] [0] [0]
[1]
01: 00 (Always 0) 01: 00 (Always 0)
02: 00 (Packet length in bytes) 02:
12 (Packet length in bytes)
03:
04:
05:
06:
07:
08:
09:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
..
30: 00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
..
00 03:
04:
05:
06:
07:
08:
09:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
..
30: 00
09
AA
0D
01
01
01
01
02
12
34
06
11
22
33
44
55
66
..
00
(CBx Response word length MSB)
(CBx Response word length LSB)
Minimum of 6 words
(CBx Response Type)
AA=Normal Response
(CBx Response Opcode)
0D=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”)
6 bytes (the Tag ID)
(CBx Response Data Byte 1)
Tag ID Byte 1
(CBx Response Data Byte 2)
Tag ID Byte 2
(CBx Response Data Byte 3)
Tag ID Byte 3
(CBx Response Data Byte 4)
Tag ID Byte 4
(CBx Response Data Byte 5)
Tag ID Byte 5
(CBx Response Data Byte 6)
Tag ID Byte 6
31: 80
Data Consistency Byte (OBDCB)
31:
81 Data Consistency Byte (IBDCB)