Request format M24LR04E-R
The request consists of:
• an SOF
• flags
• a command code
• parameters and data
• a CRC
• an EOF
Table 26. General request format
S
O
F
Request_flags Command code Parameters Data CRC
E
O
F
In a request, the “flags” field specifies the actions to be performed by the M24LR04E-R and whether corresponding fields are present or not.
The flags field consists of eight bits. Bit 3 (Inventory_flag) of the request flag defines the contents of the four MSBs (bits 5 to 8). When bit 3 is reset (0), bits 5 to 8 define the
M24LR04E-R selection criteria. When bit 3 is set (1), bits 5 to 8 define the M24LR04E-R
Inventory parameters.
Bit No.
Flag
Table 27. Definition of request flags 1 to 4
Level Description
Bit 1
Bit 2
Bit 3
Subcarrier_flag
Data_rate_flag
Inventory_flag
(1)
(2)
0
A single subcarrier frequency is used by the
M24LR04E-R
1 Two subcarrier are used by the M24LR04E-R
0 Low data rate is used
1 High data rate is used
0
The meaning of flags 5 to 8 is described in Table 28
1
The meaning of flags 5 to 8 is described in Table 29
0 No Protocol format extension Bit 4 Protocol_extension_flag
(3)
1. Subcarrier_flag refers to the M24LR04E-R-to-VCD communication.
2. Data_rate_flag refers to the M24LR04E-R-to-VCD communication.
3. Protocol_extension_flag must always be set to 0.
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M24LR04E-R Request format
.
Bit No.
Flag
Table 28. Request flags 5 to 8 when Bit 3 = 0
Level Description
Bit 5
Bit 6
Bit 7
Bit 8
Select flag
RFU
(1)
Address flag
Option flag
(1)
0
Request is executed by any M24LR04E-R according to the setting of Address_flag
1 Request is executed only by the M24LR04E-R in Selected state
0
Request is not addressed. UID field is not present. The request is executed by all M24LR04E-Rs.
1
Request is addressed. UID field is present. The request is executed only by the M24LR04E-R whose UID matches the UID specified in the request.
0 Option not activated.
1 Option activated.
0 -
1. If the Select_flag is set to 1, the Address_flag is set to 0 and the UID field is not present in the request.
Bit No.
Bit 5
Bit 6
Bit 7
Bit 8
Flag
AFI flag
Nb_slots flag
Option flag
RFU
Table 29. Request flags 5 to 8 when Bit 3 = 1
Level Description
0 AFI field is not present
1 AFI field is present
0 16 slots
1 1 slot
0 -
0 -
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