In attachment, you can download a serial program.

Via a PC or other controller you can, with minor modifications, swithch all outputs on/off.
This is a mini version of a larger program so you can understand the operation.

Comments can be found in the program itself.

What can you do:

- Placing Multiple controllers in parallel.
- Each controller appart addressable
- Adjustable or fix address.
- Go wireless ;-)
- Etc. ....

Questions can be asked here.

Good luck