FS11 messaging protocol includes the same elements as in the FD12 and PWD protocols. However, the header, footer and the polling command are different.
FS11 header
The header contains 5 characters.
SHFSiSX| Position | Name | Description | Value/Range |
|---|---|---|---|
| 1 | SH | Start of heading | 0x01 |
| 2-3 | FS | Device type |
Fixed string = "FS" |
| 4 | i | Unit identifier | 0 … 9, a … z, A … Z |
| 5 | SX | Start of text | 0x02 |
FS11 footer
The footer contains 8 characters.
EXCSUMETCRLF| Position | Name | Description | Value/Range |
|---|---|---|---|
| 1 | EX | End of text | 0x03 |
| 2-5 | CSUM | Checksum | See below |
| 6 | ET | End of transmission | 0x04 |
| 7 | CR | Carriage return | 0x0D |
| 8 | LF | Line feed | 0x0A |
Checksum calculation
The CRC-16/GENIBUS algorithm is used for calculating the checksum for the complete data message. The following table lists the parameters.
| Parameter | Value |
|---|---|
| Polynomial | 0x1021 |
| Initial Value | 0xFFFF |
| Input Reflected | False |
| Result Reflected | False |
| Result bits Inverted | True (XOR 0xFFFF) |
| Result for test input string “123456789” | 0xD64E |
FS11 example
The first character in the checksum is right after the SH of the header. The last character is the EX (end of text) character of the footer.
SHFS3SXVIS 07481 AL A BL 00582 AL 0EXBD1FET