4AO/4DI Modbus RS-485 Remote I/O 4ch analog output/4ch digital input Protocols:Modbus RTU,ASCII Watchdog timer to recover the system 3000VDC isolation protection www.advantech.com/en/products/gf-5vtd/adam-4024/mod_5e18f39b-38ef-4033-98f9-1ede917139ee