analog in SLC Remote rack

[eccan 0]

Is there any noticeable difference in response time between an NI8 analog card in a remote SLC rack (using BTR & BTW) and the same card in the main processor rack? I would assume the Block Transfers take some time, but can they happen every scan?

[Bill Linne 0]

I believe the SLC's are the same as 5's. BTW/BTR happen when the rung is true, up to and including every scan. That is NOT to say that there is no affect on scan time . . . you are correct, of course, that some amount of time is consumed by those instructions. Hence, scan time increases. What kind of input are you monitoring that requires update EVERY scan? (Just curious.) Bill

[eccan 0]

Actually, I am controlling the height of a part being swaged (staked) by using an LVDT on the stake cylinder. At the exact height required, the high pressure on the cylinder is de-energized. Every scan is probably not required, but I know I have had excellent repeatability on this process with an analog card in the main rack. This will be the first application I have built that has the analog card in a remote rack.

[Ken Moore 23]

The module update time on a NI8 is .75msec per active channel, so if all eight channels are active, the update time for the module is 6.0 msec. You only need to preform the BTW once at start up, then you can do the BTR every scan. If your distance allows go with the 230.4k baud rate. I think your application will still function the same.

[BobLfoot 302]

Addendum to what Ken said, don't try and put a Panelview or HMI station on the remote rack RIO. May have no effect, but my gut says it could.