Measurement Specialties PCI-QUAD-AC5 manual TTL to solid state relays, Unconnected inputs float

PCI-QUAD-AC5 User's Guide Functional Details

Unconnected inputs float

Unconnected inputs typically float high, but not reliably. If you are using a PCI-QUAD-AC5 board for input and have unconnected inputs, ignore the data from those lines. You do not have to terminate input lines, and unconnected lines will not affect the performance of connected lines. Ensure that you mask out any unconnected bits in software.

TTL to solid state relays

Many applications require digital outputs to switch AC and DC voltage motors on and off or to monitor AC and high DC voltages. These AC and high DC voltages cannot be controlled or read directly by the TTL digital lines of a PCI-QUAD-AC5.

Solid State Relays (SSRs) allow control and monitoring of AC and high DC voltages and provide 750 V isolation. SSRs are the recommended method of interfacing to AC and high DC signals.

The most convenient way to use solid state relays and a PCI-QUAD-AC5 board is to purchase a Solid State Relay Rack. The rack recommended for use with the PCI-QUAD-AC5 board is the SSR-PB24 from Measurement Computing Corporation.

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