Saint-Chamond worked on the 5,5 mm armor of the Renault ED whereas the 8mm machine gun from to Saint-Etienne. Then, the chassis is used for the base of the 47mm autocannons. Their protection is ensured by armored cars.
Promodel offers us to review these historical frescoes on their models:
https://www.promodels.fr/maquette-renault-ed-de-1914
Renault ED model in 1914, Olivier Saint-Lot