01-18-2007 04:22 AM
01-18-2007 08:41 AM
Rolf,
The update rate of 1.08 seconds refers to how fast/often the the A/D conversion is made in the cFP-RTD-124 module itself. This speed is determined by the hardware and is a published spec from NI.
You don't use the DAQmx driver to read cFP I/O. You will need to use the "FP Read.vi" to get the information from the module back to the computer. I usually write a loop that reads the FP I/O at a set interval and make sure the interval is longer than the update rate.
The only difference between what you are doing and having the processor module, is the location of the code that is reading the I/O modules and how fast the overall process runs.
Think of it this way, the I/O module scans the channels and performs an A2D conversion of each input. The module then makes this new data available via the backplane to a "Read" request from a program running either on a cFP processor module or a program running on another machine. The overall speed of the final system is a combination of the update rate of the I/O module, speed of network communication with the backplane and speed of the actual program.
Hope this helps.
01-18-2007 02:33 PM
01-18-2007 03:27 PM
The update rate of the [c]FP-AI-112 is determined by the filter
settings and the number of input ranges in use. Higher filter
settings and fewer input ranges yield faster update rates. Use the
following formula to determine the approximate update period:
1(
number of channels with 50 Hz filter) × 0.061 s +(
number of input ranges with 50 Hz filter) × 0.12 s +(
number of channels with 60 Hz filter) × 0.051 s +
01-18-2007 03:30 PM
Rolf,
My mistake. Here is complete calculation for "Update Rate"
Update Rate
The update rate of the [c]FP-AI-112 is determined by the filter
settings and the number of input ranges in use. Higher filter
settings and fewer input ranges yield faster update rates. Use the
following formula to determine the approximate update period:
(
number of channels with 50 Hz filter) × 0.061 s +(
number of input ranges with 50 Hz filter) × 0.12 s +(
number of channels with 60 Hz filter) × 0.051 s +(
number of input ranges with 60 Hz filter) × 0.10 s +(
number of channels with 500 Hz filter) × 0.007 s +(
number of input ranges with 500 Hz filter) × 0.012 s + 0.16 s=
Update Period01-20-2007 01:32 AM - edited 01-20-2007 01:32 AM
Message Edited by hemmerling on 01-20-2007 02:09 AM
01-22-2007 03:27 AM
01-22-2007 06:43 AM
01-22-2007 01:31 PM