We've appealed the red card so he'll be eligible for the St Johnstone game.

From the SFA site

Player: Charles Dunne, Motherwell FC has lodged a Notice of Player Reference against his dismissal.

Match: Ross County FC vs Motherwell FC on Wednesday 9th August 2017.
Competition: Scottish League Cup
Offence: A4 offence of denying a goal or an obvious goal scoring opportunity.
Fast Track Tribunal Hearing: Thursday 17th August 2017.