Hi, I have several Mitsubishi FX1S PLCs that I am using to control and monitor some machinary. Each PLC is housed alongside the machinary along with a PC (connected via the optional comms module) that is used to provide a GUI for the user to monitor and control the machinary. The problem is that we are constantly improving the software, which often requires updates to the program running on the PLC. These machines are used at several different sites around the company, so it's starting to become quite time consuming to travel out to each site and manually update each PLC. What I want to do is write an auto update module that will check a network location daily, download any new version of the PLC software and automatically write it to the PLC. Problem is I can't find any information about how I can programmatically write a new program to the PC. We currently use GX Developer-FX (v8.00). I know I can switch the PLC into stop mode by sending it a message, but does anybody know where I can find documentation of the protocol used for updatening the program. I've tried using a sniffer and recording the serial comunications from GX Developer when I do a manual PLC update, but there's just too much data to make any sense of. If anyone can help I would be really grateful. Cheers, Simon