Crate roboplc

RoboPLC

An ultimate pack of tools for creating real-time micro-services, PLCs and industrial-grade robots in Rust.

Note: the crate is actively developed. API can be changed at any time. Use at your own risk!

RoboPLC is a part of EVA ICS industrial automation platform.

DataBuffer

buf::DataBuffer covers a typical data exchange pattern when data frames are collected (cached) from a single or multiple producers, then taken by a single consumer in bulk and submitted, e.g. into a local database or into an external bus.

• always has got a fixed capacity

• thread-safe out-of-the-box

• frames may be forcibly pushed, overriding the previous ones, like in a ring-buffer.

Hub

hub::Hub implements a data-hub (in process pub/sub) model, when multiple clients (usually thread workers) exchange data via a single virtual bus instead of using direct channels.

This brings some additional overhead into data exchange, however makes the architecture significantly clearer, lowers code support costs and brings additional features.

• classic pub/sub patterns with no data serialization overhead

• based on pchannel which allows to mix different kinds of data and apply additional policies if required

• a fully passive model with no “server” thread.

pdeque and pchannel

A policy-based deque pdeque::Deque is a component to build policy-based channels.

pchannel is a channel module, based on the policy-based deque.

Data policies supported:

• Always a frame is always delivered
• Optional a frame can be skipped if no room
• Single a frame must be delivered only once (the latest one)
• SingleOptional a frame must be delivered only once (the latest one) and is optional

Additionally, components support ordering by data priority and automatically drop expired data if the data type has got an expiration marker method implemented.

Without policies applied, speed is similar to other popular channel/storage implementations. With policies data transfer speed can be lower, latency can rise, however the overall effect is significantly better as the data is processed directly inside a channel or a storage buffer.

Real-time

thread_rt::Builder provides a thread builder component, which extends the standard thread builder with real-time capabilities: scheduler policies and CPU affinity (Linux only).

supervisor::Supervisor provides a lightweight task supervisor to manage launched threads.

Modules

• buf
  Event buffers
• hub
  In-process data communication pub/sub hub
• pchannel
  Policy-based channels
• pdeque
  Policy-based data storages
• supervisor
  Task supervisor to manage real-time threads
• thread_rt
  Real-time thread functions to work with supervisor::Supervisor and standalone
• time
  Various time tools for real-time applications
• ttlcell
  A memory cell with an expiring value

Macros

• event_matches
  A macro which can be used to match an event with enum for Hub subscription condition

Enums

• DeliveryPolicy
  Message delivery policies, used by hub::Hub, pchannel::Receiver and pdeque::Deque
• Error
  The crate error type

Traits

• DataDeliveryPolicy
  Implements delivery policies for own data types

Functions

• suicide
  Terminates the current process and all its subprocesses in the specified period of time with SIGKILL command. Useful if a process is unable to shut it down gracefully within a specified period of time.

Type Aliases

• Result