I/O devices

Add a digital I/O module to the EtherCAT configuration and link its channels to Motorcortex parameters.

  2 minute read  

An I/O module brings signals such as buttons and sensors into the application, and drives lamps, relays and valves. Each channel is an entry in the module’s process data: inputs arrive in its txPDO, outputs leave in its rxPDO. You link every channel you use to a Motorcortex parameter.

Motorcortex parameter Device entry Logic/:stateToBus/status_light channel 0 EK1914rxPDO StatusLedRed output Logic/:stateToBus/status_light channel 1 EK1914rxPDO StatusLedGreen output Logic/:busToState/estop_buttons_channel1 channel 0 EK1914txPDO EStopButtonChannel1 input UserParameters/IO/startButton your own your moduletxPDO an input channel input

The status lights and the emergency stop are signals the application already has. For a channel of your own, such as a start button or a lamp, create a user parameter first.

Add the module

  1. Put the configuration in production mode and deploy it to the controller, so the ECAT tool can see the real bus.

  2. In the ECAT tool, open Add Devices, go to the From Scan tab and press Scan Bus.

  3. Select the module and press Add Devices.

    Add Devices dialog, From Scan tab: the bus scan lists four devices, and the EP2328-0001 digital I/O module at position 3 is selected

  4. Load its ESI file with next to the device name, as for CiA402 drives. The module’s channels then show up in its rxPDO and txPDO.

Create a parameter for your own channels

Add the parameters to user/parameters.json in the configuration package; they appear under root/UserParameters/. The standard configuration already has an IO branch for this:

{
  "Name": "IO",
  "Children": [
    { "Name": "startButton", "Type": "bool,input" },
    { "Name": "lamp", "Type": "bool,parameter_volatile", "Value": 0 }
  ]
}

The parameter type depends on the direction:

Channel Direction Parameter type
Input, in the txPDO device to application input
Output, in the rxPDO application to device parameter_volatile, so you can switch it from Desk or a dashboard

See user/parameters.json for all types and options.

In the ECAT tool, open the module’s rxPDO or txPDO tab, find the channel’s entry and add a link to its parameter, for example root/UserParameters/IO/startButton. For an array parameter, such as status_light, the channel number picks the element; a single value uses channel 0.

A module that is not there in simulation needs its inputs set some other way: put it in a simulated domain, or give the inputs a value with SetParameters. See Simulating devices and link files.

Check it

Deploy the configuration and open Desk. Press the button and watch its input parameter change; write 1 to an output parameter and the lamp lights up.

Next: Step 2: set the drive mode.