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The decimal and hexadecimal equivalents of some ASCII characters are shown in Table 3.2. Notice that the ASCII representation of the character “0” does not have a value of 0. Refer to Appendix C for more ASCII, decimal, and hexadecimal equivalents.
Table 3.2 - Equivalent Values
ASCII | Decimal | Hexadecimal |
|
|
|
! | 33 | 21h |
0 | 48 | 30h |
A | 65 | 41h |
D | 68 | 44h |
O | 79 | 4Fh |
R | 82 | 52h |
S | 83 | 53h |
NUL | 0 | 0h |
SOH | 1 | 1h |
STX | 2 | 2h |
ETX | 3 | 3h |
EOT | 4 | 4h |
ENQ | 5 | 5h |
ACK | 6 | 6h |
BEL | 7 | 7h |
Syntax
The command string consists of four bytes. The first byte is the start of message byte. The start of message byte is always the “!” character. The second byte is the address byte. This byte allows each unit to have a unique address. The factory default address is the ASCII “0” (zero) character. The next two bytes are the command characters. These bytes are used to specify which command the module will execute. The read A/D and digital I/O commands require an additional data byte.
Command Syntax: ! |
| _ | _ | _ |
Data Byte | ||||
2nd Command Byte | ||||
1stCommand Byte | ||||
Address Byte |
| |||
Start of Message Byte |
|
Reading A/D Channels Command
485SDA103798 Manual | 13 |
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