The National Instruments PXI-6521 is a ±30 VDC PXI Digital I/O Module designed for demanding industrial automation and control applications. Featuring 16 channels with 8 relay outputs and 8 sink/source inputs, this module operates at industry-standard 24 V logic levels, ensuring high channel isolation for increased safety and reliability. The PXI-6521 includes a keyed connector to prevent incorrect cabling, and its measurement Category II designation allows it to handle signal voltages up to 150 V, withstanding surge voltages of up to 1,500 V for enhanced durability.

The module operates using positive voltage logic, where a digital high state energizes the relay, aligning the common contact with the normally open (NO) connection, while a low state de-energizes it, orienting it to the normally closed (NC) contact in Form C relay configurations. By default, both Form C and Form A relays power up in a de-energized state, offering users the option to configure predefined power-up states through NI-DAQ with LabVIEW for consistent operation.

With the capability to monitor changes across all or selected input lines, the PXI-6521 can be programmed to trigger interrupts in response to these changes. It supports a maximum switching power of 60 W/60 VA and can manage voltages up to 150 VAC. This module requires a maximum operating current of 100 mA at 3.3 V (±5%) and 300 mA at 5 V. Designed to meet the needs of complex control environments, the PXI-6521 measures 6.3 x 3.9 inches and weighs 5.0 ounces. This device is backed by a 2-3 year warranty, and full documentation including user and maintenance manuals is available for download. For pricing details, please contact a sales representative.