It's pretty amazing that the DL305 PLCs are still going! You can connect a single C-more to the D3-340 easily, but for multiple touch panels consider the D3-422-DCU. This connects directly to the front of the CPU/PS and gives you a multi-drop DirecNET port. http://webtc1.automationdirect.com/adc/Shopping/Catalog/Programmable_Controllers/DirectLogic_Series_PLCs_(Micro_to_Small,_Brick_-a-_Modular)/DirectLogic_305_(Small_Modular_PLC)/Communications_-a-_Networking/D3-422-DCU