cFP-DO-401 fuses and flyback diodes

[Mosey]

I'm using a cFP-DO-401 to control 24V valve solenoids.

On page 4 of the cFP-DO-401 manual it says to fuse the outputs with 1.5A fast acting fuses, which makes sense. But, rather than put an in-line fuse on each of the 16 wires, does anyone know of a fuse block or module that will plug in between the cFP-CB-1 module and the cFP backplane?

Also, on page 8 of the manual, it shows that the cFP-DO-401 has flyback diodes in it, but then it says NI recommends using external ones. Why are external ones needed if the cFP-DO-401 already has them?

[Wayne.C]

Mosey,

I have never seen any kind of module that installed between the backplane and the cFP-CB-1 module.  Can't imagine why NI would ever support such a device.  I like to use DIN rail mount fuse holders for this.

NI has included internal diodes to protect the cFP-DO-401 module inputs.  A flyback diode needs to be installed as close as physically possible to the coil of a relay to provide the best protection and noise suppression.

[Mosey]

centerbolt, Thanks for the help. Where do you get the fuse holders you use?

[Wayne.C · Accepted solution]

Mosey,

Here is link to one that is available from Digi-Key.  http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=277-1569-ND  Allen Bradley also makes a line of similar parts.