National Instruments cFP-RLY-421 Relay Output Module for Compact FieldPoint

The NI cFP-RLY-421 (Part Number: 777318-421) has eight SPST electromechanical relays. This Relay Output Module is designed to be mounted on a cFP-BP-x Compact FieldPoint backplane, which delivers operational power to the module. The cFP-CB-x Connector Block has connections for the eight relay channels on the cFP-RLY-421 module, as well as for an external supply to power field instruments. If this Relay Output Module is being utilized for hazardous voltage application, then they must use the cFP-CB-1 Connector Block or an appropriate hazardous voltage cable. A hazardous voltage is considered to be greater than 42.4 Vpeak or 60 VDC. The device is equipped with a SPST, non-latching, and normally open (NO) relay type; with a relay operate time of 8 ms. Another feature is a relay release and release bounce time of 4 ms.

Every relay channel of the NI cFP-RLY-421 has two terminals: one NO (normally open) and one IC (isolated common). All of the COM terminals are linked internally and all of the VSUP terminals are also linked internally. However, National Instruments does not suggest utilizing the COM and VSUP terminals with the cFP-RLY-421 Relay Output Module. An important fact to remember is that cascading power between two modules defeats isolation between those modules. Also, cascading power from the network module defeats all isolation between modules in the FieldPoint bank. The device has a recommended operating temperature of – 40 to 55 °C. It has a maximum AC switching power of 375 VA, and a maximum DC switching power of 60 W.

To link loads to the National Instruments cFP-RLY-421 Relay Output Module, the user must wire an external power supply to the load and the IC terminal of the separate channel. The user can install a 1.5 A, 250 V maximum, quick-acting fuse appropriate for the load at the IC terminal to protect the module and the load from harm. The device has a weight of 4.8 oz., with the dimensions: 4.3 x 4.3 x 3.6 in. It has an expected mechanical life of 2 × 107 operations minimum, an expected electrical life of 100,000 operations. As the cFP-RLY-421 is a UL recognized component, the system must be installed in a NEMA, IP, or UL listed enclosure to ensure safe use.