1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48

//! Sans-IO implementation of the ANSI X3.28 serial line protocol
//!
//! X3.28 is an old field bus protocol, commonly used on top of a RS-422 bus.
//! The bus settings should be 9600 baud, 7 bit char, no flow control, even parity, 1 stop bit (7E1).
//! Since this crate doesn't provide IO at all, feel free to use whatever transport you want.
#![deny(missing_docs)]

pub mod master;
pub mod node;

pub use master::Master;
pub use node::NodeState;
pub use types::{
    Address, Error as TypeError, IntoAddress, IntoParameter, IntoValue, Parameter, Value,
};

mod buffer;
mod nom_parser;
mod types;

mod ascii {
    /// Acknowledge
    pub const ACK: u8 = 6;
    /// Backspace
    pub const BS: u8 = 8;
    /// Enquiry, terminates a parameter read
    pub const ENQ: u8 = 5;
    /// "End of transmission", sent as first byte of each command
    pub const EOT: u8 = 4;
    /// End of text, sent after parameter value
    pub const ETX: u8 = 3;
    /// Negative ACK
    pub const NAK: u8 = 21;
    /// Start of text, separates address and parameter in a write command
    pub const STX: u8 = 2;
}

/// Calculates the BCC checksum according to the X3.28 spec.
pub(crate) fn bcc(data: &[u8]) -> u8 {
    let mut checksum: u8 = 0;
    for byte in data {
        checksum ^= *byte;
    }
    if checksum < 0x20 {
        checksum += 0x20;
    }
    checksum
}