6442S, the dedicated cable between the controller module and the HMI module is only about 2 meters long, can this cable be extended?

It‘s ok.Cloudray can provide you with extension cords according to your needs

How do I order the HMI Extension for 6442G,

Hi Richard,
This product is not yet available in our store. If you need it in the future, you can give us feedback and we will list it in the store. The HMI cable we can provide is up to 3m long.