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National Instruments OP-8913 Digital I/O Module

The National Instruments OP-8913 is a 32-channel digital I/O module with fault insertion that is LVTTL/TTL and made for switch load signal conditioning (SLSC). With support for 16 digital input and 16 digital output LVTTL/TTL channels, this module provides extensive fault-insertion capabilities for every signal. Users are able to set the channels as push-pull, sourcing, sinking, or sourcing inputs in addition to sourcing or sinking outputs. Thanks to its rear transition interfaces and suitable cabling, the OP-8913 can be used in a wide range of industrial applications, supporting both PXI and CompactRIO devices.

A complex Fault Insertion Unit (FIU) with 112 relays total—seven relays for each differential pair of signals—is included into the OP-8913. Because each relay is independently adjustable, precise fault insertion management is possible. For each signal in the pair, the user-supplied voltage references (VBusA and VBusB) can be simulated by the FIU together with a variety of fault states, such as open-circuit and short-circuit faults. Digital I/O systems can be thoroughly tested and validated under many fault scenarios because to this flexibility.

The OP-8913 operates safely and dependably thanks to embedded safeguards. When everything is in its default condition, every relay is open and every channel is updated at once. Short circuits are prevented when VBusA and VBusB are not connected to the same channel at the same time. Only one more fault is allowed for VBusA or VBusB on a channel pair when Signal + and Signal - are shorted together. In order to ensure safe transitions and avoid unintentional faults, the relays on a channel are always open before closing any others.

With a response time of less than 0.5 milliseconds, the FIU's relay technology provides large density. Still, even for a few microseconds, peak currents might cause problems for this technology. Due to the presence of cabling and a capacitor in the circuit, users must connect resistors to the signal or VBus in order to control peak current. Although the VBus has a 0.1A power supply restriction, the presence of a capacitor at the output can lead to peak currents exceeding 5A before the internal current limit kicks in, which could break the relay irreversibly. A Return Material Authorization (RMA) for card repair may be provided in the event of a relay failure in short mode.