vsPLC is a software PLC developed in node-red with a light and clean dashboard to monitor the PLC status and the memory registers set via Modbus TCP. The vsPLC purpouse is to have a virtual ModbusTCP PLC that can be used in lab to simulate a real PLC.
vsPLC can be programmed via ModbusTCP, it listen for ModbusTCP commands on port TCP/502 (it can be customized in node-red configuration). The vsPLC has four Holding Registers (address from 0 to 3) that can be set with integer values (0–255) and five Coil Registers that can be set with 0 or 1 bits values. Device ID is set to 1. More Registers can be added if needed.
The dashboard shows the registers current values:
- Coil Registers are showed on left side of the dashboard, each register value is showed (1/0).
- Holding Registers are showed in the middle of the dashboard, each register value is showed with a gauge chart (gauge values can be customized), for each register a historic chart is showed with values registered in the last minute.
Node-red need to be installed on the target machine, the following modules need to be installed before importing the vsPLC flow:
- node-red-contrib-modbus
- node-red-contrib-buffer-parser
- node-red-node-random
- node-red-dashboard
- node-red-contrib-ui-digital-clock
The procedure to import node-red modules can be find here. You can use palette manager to install all the modules. Is suggested to run node-red as a service and to start on boot.
Import the vsPLC flow json configuration into node-red, follow node-red instructions here
When using Docker, flow is automaticaly import.
# docker run --rm -p 1880:1880 -p 502:502 --name vsPLC mguyard/vsplc:latest
version: "3.3"
name: vsPLC
services:
vsplc:
container_name: vsPLC
image: mguyard/vsplc:latest
ports:
- 1880:1880
- 502:502
restart: unless-stopped
Once the json flow is deployed and started vsPLC is ready to run.
To open the vsPC dashboard open in a browser the page http://your_machine_ip:1880/ui (port 1880 is the node-red standard port).
Https can be enabled in your node-red installation, reference here.
To set some modbus values visible in vsPLC, you can deploy a container with CLI below :
# docker run --rm -ti -e MODBUS_PLC=<your_vsPLC_docker_IP> --name modbus-client mguyard/modbus-client:latest
It's also possible to don't define environment variable -e MODBUS_PLC=<your_vsPLC_docker_IP> in Docker container creation but run.py script will require an --ip argument.
This command will prompt you a bash and you will be able to run python3 run.py if MODBUS_PLC is define in docker environment variable.
If MODBUS_PLC environement variable isn't define in Docker container, please use commande python3 run.py --ip <your_vsPLC_docker_IP>
Press Enter to stop the script