Crate scpi[−][src]

Expand description

This crate attempts to implement the IEE488.2 / SCPI protocol commonly used by measurement instruments and tools.

It does not require the std library (ie it’s no_std compatible) or a system allocator (useful for embedded).

API is unstable (as of 0.2.*)

Scope

The crate does not support any transport layer, it only reads ascii-strings ([u8]) and writes ascii responses.

It does not implement any higher level functions/error handling other than SCPI parsing and mandated registers/commands(optional).

Using this crate

Add scpi to your dependencies:

[dependencies]
scpi = "0.x"

The API is still work in progress so the minor version should be specified.

Features

These features are by default turned OFF.

extended-error - Allows extended error messages of the form <error code>, "error message;extended message". Requires more data and program memory.
std - Use std library, note that libm feature can be disabled with std.

These features are by default turned ON.

libm - Uses libm for no_std operation on stable.
unit-* - Creates conversion from a argument [and suffix] into corresponding uom unit. Disable the ones you don’t need to save space and skip uom.

Getting started

Look at the example for how to create a tree and run commands.

Character coding

SCPI is strictly ASCII and will throw a error InvalidCharacter if any non-ascii (>127) characters are encountered (Exception: Arbitrary data blocks). This library uses ASCII [u8] and not Rust UTF-8 str, use to/from_bytes() to convert in between them.

String/arbitrary-block data may be converted to str with the try_into trait which will throw a SCPI error if the data is not valid UTF8.

Error handling

The Context::run(...) function aborts execution and returns on the first error it encounters. Execution may be resumed where it aborted by calling exec again with the same tokenizer.

User commands will often use functions which may return an error, these should mostly be propagated down to the parser by rusts ? operator.

The documentation often uses the term ‘throw’ for returning an error, this should not be confused with exceptions etc which are not used.

Limitations and differences

These are the current limitations and differences from SCPI-99 specs (that I can remember) that needs to be addressed before version 1.0.0. They are listed in the rough order of which I care to fix them.

Response data formatting, currently each command is responsible for formatting their response. Done
Better command data operators with automatic error checking. TryInto and TrayFrom traits are implemented for Integer, float and string types
Automatic suffix/special number handling. Supports all SCPI-99 simple suffixes and decibel
Provide working implementation of all IEEE 488.2 and SCPI-99 mandated commands. All IEEE488.2/SCPI-99 mandated commands have default implementations.
Quotation marks inside string data, the parser cannot handle escaping ' and " inside their respective block (eg “bla ““quoted”“ bla“). The parser properly handle '' and "" but it’s up to user to handle the duplicate
Expression data, not handled at all. Supports non-nested numeric-/channel-list expressions
Provide a reference instrument class implementation
Error codes returned by the parser does not follow SCPI-99 accurately (because there’s a fucking lot of them!).
Working test suite. Better than nothing I suppose

Nice to have

Not necessary for a 1.0.0 version but would be nice to have in no particular order.

Double-precision float (f64) support.

Contribution

Contributions are welcome because I don’t know what the fuck I’m doing.

Project organisation:

example - A simple example application used for testing
scpi - Main library
scpi_derive - Internal macro support library, used by scpi to generate error messages and suffixes (enter at own risk)

Re-exports

pub use scpi1999 as scpi;

Modules

command	Command trait and helper functions.
error	This module contains standard SCPI errors in the form of the Error enum.
expression	Special cases of expressions
format	Wrappers to format and discriminate SCPI types
ieee488	Contains IEEE 488.2 parser and mandatory commands
option
prelude	Prelude containing the most useful stuff
response
scpi1999	Contains SCPI modules and mandatory commands
suffix
tokenizer
tree	Used to build a SCPI command tree
util

Macros

ieee488_cls
ieee488_ese
ieee488_esr
ieee488_idn
ieee488_opc
ieee488_rst
ieee488_sre
ieee488_stb
ieee488_tst
ieee488_wai
nquery	Creates a stub for query()
qonly	Creates a stub for event()
scpi_status	Create a `STATus:` tree branch
scpi_system	Create a `SYSTem:` tree branch
scpi_tree