National Instruments OAC5A 用户手册

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 National Instruments Corporation

To set up and use the SSR Series modules and backplanes you need 
the following:

❑

SSR Series module backplane kit and documentation

❑

SSR Series module

❑

National Instruments DAQ device

❑

Cable and/or SC-205X device

❑

Number 1 and number 2 Phillips-head screwdrivers

❑

¼ in. flat-head screwdriver

SSR modules optically isolate the field signals from the computer, 
preventing any possibility of damage to the computer by overvoltage 
transients on these lines. The optical isolation is rated for surges up 
to 4,000 V.

Input SSR modules sense voltages from a field source and return a logic 
value to the National Instruments DAQ device. If a voltage within the 
selected input range for the input module is present, it returns a logic low 
signal to the DAQ device, otherwise it returns a logic high signal.

Output SSR modules sense a logic value from the DAQ device to control 
external devices. They control power in a manner similar to conventional 
relays. If the DAQ device sends a logic low signal, the output module turns 
on and current flows. If the DAQ device sends a logic high signal, the 
output module turns off.

Output SSR modules are similar to conventional relays, but there are some 
important differences. Unlike conventional relays, these solid state relays 
require voltage on the load side. Current needs to flow through them in the 
on state, or they turn off even if a logic low signal is at their input. This 
occurrence is referred to as dropout. If a solid state relay drops out, you 
must turn it off with a logic high signal before you can turn it on again.