Built on a 3U PXI card, the GX5641 provides 64 bidirectional TTL or differential channels, for 128 individual digital inputs or outputs. The card's channels can be predefined to convert TTL to differential or vice versa. You can operate the GX5641 I/O card independently or control it through software. Geotest-Marvin Test Systems, www.geotestinc.com.