# yaads v0.1.0 - Table of Contents

> Beckhoff ADS in pure Elixir: a client for TwinCAT PLCs that reads, writes and watches variables by name, over TCP or Secure ADS (TLS), and finds PLCs and adds and deletes routes over UDP, without C in the BEAM.

## Pages

- [yaads](readme.md)
- [Changelog](changelog.md)
- [LICENSE](license.md)
- [NOTICE](notice.md)

## Modules

- Client
  - [ADS](ADS.md): ADS, Beckhoff's Automation Device Specification, in pure Elixir, as a client: reading, writing
and watching the variables of a TwinCAT PLC by name, over TCP or over Secure ADS (TLS).
  - [ADS.Adapter](ADS.Adapter.md): A network adapter of a TwinCAT system, as its system service lists them, for
`ADS.Client.adapters/2`: index group 701, `SYSTEMSERVICE_IPHELPERAPI` in Beckhoff's
Tc2_Utilities, offset 1, `IPHELPERAPI_ADAPTERSINFO`, on AMS port 10000. A read of 4 bytes
answers the size of the whole list; a read of less than that, `:device_invalid_size`.
  - [ADS.Client](ADS.Client.md): A connection to an ADS device, usually a TwinCAT PLC, over TCP or Secure ADS.
  - [ADS.Codepage](ADS.Codepage.md): The code page of the strings of one byte to a character a TwinCAT system has: its PLC's
`STRING`s, the names and comments of its symbols and types, and the strings of its system
service and router, such as its host name, routes and adapters. Windows-1252 unless told
otherwise, with `codepage:` to `ADS.Client`, `ADS.Discovery` and the mix tasks, as Beckhoff's own
libraries read them on Western Windows; a system on Windows of another language has that one's.
  - [ADS.DataType](ADS.DataType.md): A PLC's description of one of its data types: a structure and its members, an array, an
enumeration and its values, or another name for a type.
  - [ADS.Discovery](ADS.Discovery.md): Finding ADS devices on the network, and adding routes to them, over UDP port 48899, as
TwinCAT's own Broadcast Search and Add Route do
  - [ADS.ReturnCode](ADS.ReturnCode.md): The return codes of ADS, which a device or a router answers with when something goes wrong.
  - [ADS.Route](ADS.Route.md): A route of a TwinCAT system, as its system service lists them, one entry at a time, for
`ADS.Client.routes/2`: index group 803, `SYSTEMSERVICE_ENUMREMOTE` in Beckhoff's Tc2_Utilities,
on AMS port 10000, the entry's index as the offset. After the last, the system answers
`:device_no_more_handles`.
  - [ADS.Symbol](ADS.Symbol.md): A PLC's description of one of its variables: its name, the name of its type, where it is, and
how big.

- Values
  - [ADS.Type](ADS.Type.md): The data types of a TwinCAT PLC, and their values as Elixir terms.

- Secure ADS
  - [ADS.Certificate](ADS.Certificate.md): X.509 certificates for Secure ADS, as DER binaries.
  - [ADS.Secure](ADS.Secure.md): Secure ADS: ADS inside TLS 1.2, to port 8016, from TwinCAT 3.1 build 4024 on.

- Encoding
  - [ADS.AMS](ADS.AMS.md): AMS packets, which carry every ADS command and response: a 32-byte AMS header with the addresses
of both ends, the command, flags, the length of the data, an error code and an invoke id, then
the data. All numbers are little-endian.
  - [ADS.Command](ADS.Command.md): The nine ADS commands: the data of their requests and of the responses to them, inside AMS
packets (see `ADS.AMS`). All numbers are little-endian.
  - [ADS.NetId](ADS.NetId.md): AMS NetIds: six numbers from 0 to 255, written with dots like an IP address with two more parts,
and sent as six bytes in that order.
  - [ADS.Sum](ADS.Sum.md): Sum commands: many reads, writes, or read-writes in one ADS read-write, to an index group of the
system services with the number of them as index offset.

## Mix Tasks

- [mix ads.info](Mix.Tasks.Ads.Info.md): Finds the PLCs on the network, as `mix ads.route` does, and shows what one's system service
answers: its version and state, its host name and its network adapters. It answers only to a
machine it has a route for, which `mix ads.route` adds.
- [mix ads.route](Mix.Tasks.Ads.Route.md): Finds the PLCs on the network, and adds a route on one for this machine with the login of a user
on it, so that `ADS.Client` can connect; then connects, to see that it can