We are upgrading AR-727CM 4DI4DO to 8DI4DO. The old AR-727CM-V3-4I4O is phased out and is replaced by the new AR-727CM-V3-8I4O since 2018 Sept. The feature is added but the price is same! With more DI input contact, the application will be more extensive , it is also compatible with Modbus protocol and SOYAL 727 APP . Please contact SOYAL for more details.