System for sending PLC data and production line video across countries, for automotive parts factories, Cambodia–Thailand.

How the brief came about

The challenge in this case was to let the team in Thailand see machine data and footage of the production line in Cambodia without waiting for on-site staff to send it. The values recorded by the PLC and the footage at the workstation existed only at the factory, so people in another country found it hard to answer questions about how the line had run in the past.

This work covers cross-border data and video transfer, not an AI quality inspection system. The cameras here record footage for people to review later. They do not use AI to decide whether a workpiece is good or defective.

Requirements and constraints

The system had to work with the equipment and network on site in another country. The main requirements and constraints are as follows.

• Machine data comes from the PLC and data logger on the line, which had to be tested first to confirm that values could be read.
• Cross-border data transfer uses a mobile internet SIM, so speed and remote access had to be tested on the actual site.
• Positions for the IoT Control Box, cameras, LAN cables and power sockets had to be set within a production line already in use.
• The software runs on the Ubuntu operating system and is developed in Python.
• Images from inside the factory are internal data and are not released to the public.

How does this cross-border data and video transfer system work?

This system sends machine data across the border as files. Values from the PLC are recorded as CSV files on site. The IoT Control Box receives those files and sends them across the border back to Thailand. Video from the cameras is stored in the box, and the team in Thailand views it through a web page.

This approach matches the requirements agreed with the customer: transferring existing CSV files and viewing video online. The customer's system contractor extracts values from the PLC into CSV files, while we handle everything from the IoT Control Box through to the web page. Each team can therefore do its own work, with the CSV file as the handover point.

Deliverables

What we delivered in this work includes both on-site equipment and software, as follows.

• 1 IoT Control Box, designed, built and installed on the production line
• 2 IP cameras: a workstation camera (Single Camera) and a camera with an overview of the line (Overview Camera)
• Software that sends CSV files recorded from the PLC across the border back to Thailand
• Storage of camera video in the IoT Control Box
• A simple web page for viewing video online

Why was this work split into a survey phase and an installation phase?

This work was split into 2 phases because it first had to be confirmed that values could be read from the PLC and that the on-site network could transfer files across the border. Only then was the actual equipment installed. The work sequence was as follows.

1. 2019, survey phase: tested reading values from the PLC and data logger, tested mobile internet SIMs from 2 carriers, tested remote access and cross-border file transfer, and set the installation positions for the box, cameras, LAN cables and power sockets
2. 2020, installation phase: installed 1 IoT Control Box and 2 IP cameras with the software on the delivery list, followed by acceptance in March 2020

Confirmed results from the acceptance documents

The acceptance document (Exit Criteria) dated March 2020 states that 3 software items and 2 hardware items were fully completed. The team in Thailand could open PLC data files and recorded video of the production line in Cambodia remotely.

During acceptance, users asked for the video files to be sorted by time period. We made this change so that they could find the period they needed more easily. This case has no business performance figures, so we report only results confirmed by documents.

What we learned

This work offers 3 principles for transferring data from overseas factories.

• Test the network and data reading points on site before installing equipment. Cross-border work has variables that cannot be tested from elsewhere, including SIM signal, remote access and space for the box. Separating the survey phase from the installation phase revealed these constraints before equipment was installed.
• The network needs a support plan from the start. In this work, the internet SIM in Cambodia was on a monthly plan, and the project summary recorded this as an issue. If the SIM expires, the system stops sending data.
• Organise data the way users search for it. Remote users mainly review recordings by time period, so video files should be sorted by time from the design stage. In this work, users requested this as an addition during acceptance.

How this approach can apply to your factory

If your factory has a production base in another country and the PLC already records data to files, you can use the same approach as this case: receive the files on site, send them across the border and store video for later review. What needs adjusting is the method of extracting data, the camera positions and the network at your site.

Beyond this table, set the data transfer frequency to suit actual use. Sending more often than necessary uses more network capacity with no added benefit.