.. _io-can:

CAN Communication
=================

You can find the command set at :ref:`io-command-set`.

Addresses
---------

The base address to receive messages is set to ``0x100`` by default.

The addresses used by the IOBoard are calculated from the base address by adding the following offsets.

======================= =======
Offset to base address  Message
======================= =======
``+0``                  Receive commands
``+1``                  Answer to ``CMD_IOBOARD_CONNECT``
``+2``                  Answer to ``CMD_IOBOARD_GETDIGIN``
``+3``                  Answer to ``CMD_IOBOARD_GETANALOGIN``
======================= =======


Commands
--------

In the following, the CAN IDs are given as an offset to the base address,
so ``+3`` means base address plus 3.


CMD_IOBOARD_CONNECT
*******************

Use this command to test the connection to the IOBoard.

Command
   ID: ``+0``

   =============== = = = = = = =
   ``CMD_CONNECT`` 0 0 0 0 0 0 0
   =============== = = = = = = =

Answer
   ID: ``+1``

   =============== = = = = = = =
   ``CMD_CONNECT`` 1 2 3 4 5 6 7
   =============== = = = = = = =


CMD_IOBOARD_GETDIGIN
********************

The command requests data from all digital inputs.

Command
  ID: ``+0``

  ======================== = = = = = = =
  ``CMD_IOBOARD_GETDIGIN`` 0 0 0 0 0 0 0
  ======================== = = = = = = =

Answer
  ID: ``+2``

  ======================== ========= ======== = = = = =
  ``CMD_IOBOARD_GETDIGIN`` Bits 8-15 Bits 0-7 0 0 0 0 0
  ======================== ========= ======== = = = = =

Note that for electrical reasons the digital inputs are flipped:
A value of ``1`` means that the respective input is low, a value
of ``0`` means it is high.


CMD_IOBOARD_SETDIGOUT
*********************

The command sets all digital outputs. The outputs are organized as follows:

====== =======================
Port D 8 x optocoupler outputs
Port G 4 x optocoupler outputs
Port B 4 x relay outputs
====== =======================

Command
  ID: ``+0``

  ========================= = ====== ==================================== = = = =
  ``CMD_IOBOARD_SETDIGOUT`` 0 Port D Port G (Bits 4-7), Port B (Bits 0-3) 0 0 0 0
  ========================= = ====== ==================================== = = = =

Answer
  No answer.


CMD_IOBOARD_GETANALOGIN
***********************

The command requests data from analogue inputs.

Command
  ID: ``+0``

  =========================== = = = = = = =
  ``CMD_IOBOARD_GETANALOGIN`` 0 0 0 0 0 0 0
  =========================== = = = = = = =

Answer
  ID: ``+3``

  =========================== ========== ========== ========== ========== ========= = =
  ``CMD_IOBOARD_GETANALOGIN`` low bits 1 low bits 2 low bits 3 low bits 4 high bits 0 0
  =========================== ========== ========== ========== ========== ========= = =

  The `high bits` byte contains the high two bits for each channel,
  in ascending order (Bits 0-1 for channel 1 and so on).


CMD_IOBOARD_GETALLDATA
**********************

The command requests data from both the digital and the analog inputs.
It has the same effect as requesting the digital and analog inputs separately.

Command
  ID: ``+0``

  ========================== = = = = = = =
  ``CMD_IOBOARD_GETALLDATA`` 0 0 0 0 0 0 0
  ========================== = = = = = = =

Answer
  The answer consists of two CAN frames that are identical to the answer frames to
  the commands ``CMD_IOBOARD_GETDIGIN`` and ``CMD_IOBOARD_GETANALOGIN``.