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[READ-ONLY] Mirror of https://github.com/SantaClaas/embedded-fan-control.
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2.4 kB · 64 lines
Rust
at main
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465use crate::modbus;
/// The most registers one request may ask for. The fan answers with at most 80 bytes and refuses/// anything longer with exception `0x03`./// See MODBUS Parameter RadiCal im Spiralgehäuse V1.00, section 1.3.2pub(crate) const MAX_COUNT: usize = 37;
/// Reads a run of input registers, which hold the values the fan measures about itself and which/// cannot be written. Unlike [`super::ReadHoldingRegister`] this asks for a range rather than a/// single register, because the values worth polling sit next to each other and a range costs the/// same round trip as one register would.////// `COUNT` is part of the type so the request and the array it is answered with cannot disagree/// about how many registers are in flight./// See MODBUS Parameter RadiCal im Spiralgehäuse V1.00, section 1.3.2pub(crate) struct ReadInputRegisters<const COUNT: usize>([u8; 8]);
impl<const COUNT: usize> ReadInputRegisters<COUNT> { pub(crate) fn new( device_address: modbus::device::Address, start_address: modbus::register::Address, ) -> Self { // The fan reports both of these as exception `0x03`, which says only that the answer would // be the wrong length. Catching them here names the actual mistake, at compile time const { assert!(COUNT >= 1, "a request for zero registers is refused by the fan"); assert!( COUNT <= MAX_COUNT, "more registers than fit in the fan's 80 byte answer" ); }
let start_address = start_address.to_be_bytes(); let count = (COUNT as u16).to_be_bytes(); let mut data = [ *device_address, modbus::function::code::READ_INPUT_REGISTERS, start_address[0], start_address[1], count[0], count[1], // CRC set in next step 0, 0, ];
let checksum = modbus::CRC.checksum(&data[..6]).to_be_bytes();
// They come out reversed (or is us using to_be_bytes reversed?) data[6] = checksum[1]; data[7] = checksum[0]; Self(data) }
pub(crate) fn device_address(&self) -> modbus::device::Address { self.0[0].into() }}
impl<const COUNT: usize> AsRef<[u8]> for ReadInputRegisters<COUNT> { fn as_ref(&self) -> &[u8] { &self.0 }}