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Response Packet Format
Response packets refer to packets transmitted by the SKB switch for the purposes of returning
query data. Response packets have an identical format as a standard command packet, with the
MSB of the opcode byte set.
If, for example, an opcode of 0x01h was sent to the SKB switch and this opcode represented a
query, the response packet has an opcode of 0x81h.
The length byte of a response packet represents the total length of the parameter response data,
regardless of the actual data types embedded in the parameter area.
Parameter Data Types
Parameter data of the command packet is limited to 254 bytes, which can be allocated at the
discretion of the application according to standard data types shown in Table 10.
Table 10: Parameter Data Types
Data Type
signed char
1 (8)
unsigned char
1 (8)
signed int
2 (16)
unsigned int
2 (16)
signed long
4 (32)
unsigned long
4 (32)
float
4 (32)
Byte Order
When utilizing data types larger than one byte, the byte order follows "little-endian" convention:
the low-order byte (which holds the least significant bit, or LSB) is referenced as byte 0.
Subsequent bytes progress toward the high-order byte (which holds the MSB). This sequence is
illustrated as follows.
Single-byte bit order:
Bit
7
6
5
4
Double-byte bit order:
Bit
15
14
13
Size in Bytes (Bits)
3
2
1
0
12
11
10
9
Byte 0 (low)
8
7
6
5
Byte 1 (high)
Operating and Maintenance Instructions – 31
4
3
2
1
0
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