biancode / netpi-nodered-npix-rs485 Goto Github PK

Made for netPI, the Open Edge Connectivity Ecosystem

The image provided hereunder deploys a container with installed Debian, Node-RED and rs485 nodes to communicate with an extension module NIOT-E-NPIX-RS485.

Base of this image builds the latest version of debian:stretch with installed Internet of Things flow-based programming web-tool Node-RED and two extra nodes serial rs485 (in/out) providing access to the RS485 serial port of the module NIOT-E-NPIX-RS485. The nodes communicate to the module across a serial connection over device /dev/ttyS0.

ATTENTION! Never plug or unplug any extension module if netPI is powered. Make sure a module is already inserted before applying 24VDC to netPI.

The software includes modified third party software from the Github repository serialport which is distributed in accordance with the Apache license, Version 2.0.

To allow the access to the Node-RED programming tool over a web browser the container TCP port 1880 needs to be exposed to the host.

Only the privileged mode option lifts the enforced container limitations to allow usage of GPIOs in a container needed for the node serial rs485(out) to control the transmit/receive mode of the module's rs485 transceiver across GPIO 17.

Controlling GPIO 17 is done in software causing a jitter. An oscilloscope has shown that GPIO is set to high state (transmit mode) 400usec up to 1ms before data is transmitted and falls back to low state (receive mode) 5ms to 32ms after the last bit has been shifted out of the transmit shift register. Consider that only after that time the module is able to receive data again.

The serial port device /dev/ttyS0 needs to be added to the container. The device is available only if an inserted module has been recognized by netPI during boot process. Else the container will fail to start.

STEP 1. Open netPI's landing page under https://<netpi's ip address>.

STEP 2. Click the Docker tile to open the Portainer.io Docker management user interface.

STEP 3. Enter the following parameters under Containers > Add Container

• Image: biancoroyal/biancode/netpi-nodered-npix-rs485

• Port mapping SSH: Host "22" (any unused one) -> Container "22"

• Port mapping Modbus: Host "502" (any unused one) -> Container "502"

• Port mapping Node-RED: Host "1880" (any unused one) -> Container "1880"

• Port mapping Modbus server: Host "10502" (any unused one) -> Container "10502"

• Port mapping Modbus Flex server: Host "11502" (any unused one) -> Container "11502"

• Restart policy" : always

• Runtime > Devices > add device: Host "/dev/ttyS0" -> Container "/dev/ttyS0"

• Runtime > Privileged mode : On

STEP 4. Press the button Actions > Start container

Pulling the image from Docker Hub may take up to 5 minutes.

After starting the container open Node-RED in your browser with http://<netpi's ip address>:<mapped host port> e.g. http://192.168.0.1:1880. Two nodes serial rs485 (in/out) in the nodes npix library palette provides you access to the RS485 interface of the NPIX module. The nodes' info tab in Node-RED explains how to use them.

The container starts the SSH service automatically.

Login to it with an SSH client such as putty using netPI's IP address at your mapped port. Use the credentials root as user and root as password when asked and you are logged in as root user root.

Use debian commands as usual.

• hilscher/netPI-nodered-npix-rs485:latest - non-versioned latest development output of the master branch. Can run on any netPI system software version.

The image is built from the GitHub project netPI-nodered-npix-rs485. It complies with the Dockerfile method to build a Docker image automated.

View the license information for the software in the Github project. As with all Docker images, these likely also contain other software which may be under other licenses (such as Bash, etc from the base distribution, along with any direct or indirect dependencies of the primary software being contained). As for any pre-built image usage, it is the image user's responsibility to ensure that any use of this image complies with any relevant licenses for all software contained within.

To build the container for an ARM CPU on Docker Hub(x86 based) the Dockerfile uses the method described here resin.io.

Hilscher Gesellschaft fuer Systemautomation mbH www.hilscher.com