Number of Bidirectional Digital Channels: 4. Digital I/O Isolation: None. Current Flow Direction: Sinking Input, Sinking Output, Sourcing Input, Sourcing Output. Front Connection Type: BNC. Conformal Coated: No. Enclosed: Yes. Number of Digital Output Only Channels: 0. Number of Digital Input Only Channels: 0. Digital I/O Logic Levels: 3.3V TTL. Maximum Update Rate: 55 ns.