GPIO protocol

Supported device types and versions
Communication line configuration
Communication station configuration
I/O tag configuration
Literature
Changes and modifications
Document revisions

Kotva
typy_verzie0 typy_verzie0

Supported device types and versions

...

Protocol supports communication via GPIO (General Purpose I/O) interface on inputs/outputs of Raspberry PI and computers built on a RPI Compute Module. Currently supported are:

• Raspberry PI (version 2 and 3) based on pigpio library - communication via GPIO (General Purpose I/O) pins
• Techbase NPE - X500 M3  (DIN-mounted industrial computer built on RPI Compute Module 3 with optional industrial inputs and outputs)

The communication was tested with Raspberry PI (version 3) and NPE - X500-M3-MAX-3G.

The protocol allows For Raspberry PI, the protocol supports reading of digital inputs (instantaneous values as well as counting signal changes with an optional time filter) and setting digital outputs to a constant value or pulse-width modulation (PWM).

For NPE X500 the protocol supports reading of digital and analog inputs and status of user button and analog inputs (in case of NPE-X500 also a value of user button), writing to digital outputs (for NPE-X500 also , setting relay outputs, working with user LEDs and a buzzer.

Note: On Raspberry PI, the KOM process must be run under the root user to gain access to the GPIO. It is possible to achieve by setting the setuid bit for the kom binary. Under the user pi, you can do the following:

cd /opt/d2000/bin
sudo chown root kom
sudo chmod 4755 kom

Note: On NPE X500, the KOM process must be run under the root user to gain access to the GPIO (see the previous note for Raspberry PI). An alternative is adding user d2000 to groups and setting appropriate access rights. Under the root user, you can do the following:

sudo usermod -a -G gpio d2000

For access to serial ports also:

sudo usermod -a -G dialout d2000

In order for the d2000 user to access the LEDs and the buzzer, it is necessary to set the rights for the respective files each time the computer starts up. Create a file d2000init in the /etc/init.d directory containing:

#!/bin/bash

### BEGIN INIT INFO
# Provides:          script
# Required-Start:    $all
# Required-Stop: 
# Default-Start:     2 3 4 5
# Default-Stop:     
# Short-Description: D2000Kom
# Description:       Support for D2000 KOM (work with leds/buzzer)
### END INIT INFO

DESC="Set permissions for LED/BUZZER for D2000 KOM"
chmod -R o+w /sys/class/leds/LED1
chmod -R o+w /sys/class/leds/LED2
chmod -R o+w /sys/class/leds/BUZZER

Then run:

chmod 755 /etc/init.d/d2000init
update-rc.d d2000init defaults

Kotva
komunikacna_linka0 komunikacna_linka0

Communication line configuration

...

Kotva
komunikacna_stanica0 komunikacna_stanica0

Communication station configuration

...

The address format of the I/O tag depends on the device type.

I/O tag addresses for Raspberry PI

In the following table, id defines the number of ping in BCM (Broadcom) numbering.

Following image copied from http://pinout.xyz shows the BCM pin numbering on the GPIO connector:

Image Added

I/O tag addresses for NPE NPE- X500

In the following table, id defines the number of input/output (e.g. DI, DO, AO). The number of inputs and outputs depends on the particular model. The notes are referring to the NPE - X500-M3-MAX-3G that was tested.
Note 1: Output points whose addresses contain _BUF use a buffered writing. This allows the values of such objects not only to be written, but also to be read, which can be useful, for example, after the start of the KOM process.
Note 2: With the tested model, the reading of the digital input took less than 1 ms, while the reading the analog input took approximately 20 ms.

Kotva
literatura0 literatura0

Literature

...