The Industrial Raspberry Pi Forum

• Is 5 ms sample rate the fastest rate when reading 4 channels in parallel? Will this increase to 20 ms when reading 16 channels in parallel? Will it also drop to 1,25 ms when reading 1 channel?
• What is limiting the sample rate: Is that the software “loop” running on the cpu (python?), the bus that the adc’s are attached to, or is it the adc’s themselves?
• Are there sample and hold circuits in use, so that each channel can be sampled at the same time (and then all samples be stamped with the same time-stamp), or will the channels be read out/sampled at different times in sequence?

Hi,
you have two cycle rate:
The 5 ms cycle time is on the piBridge for each AIO module. 10ms for two, 15 ms for three and so on. If you use DIOs also, it will increase by about 2.5ms per DIO.
The 5 ms per AIO do not depend on the configuration.
The duration of the last IO-cycle on the piBridge is written to the variable RevPiIOCycle (piTest -r RevPiIOCycle).

The second rate is inside the AIO. This can be configured in pictory with the value ADC_DataRate. This defines how fast the ADC samples the values. This affects the accuracy of the values. Please have a look in the tutorial for more details.

The limiting sample rate is of course the lower one.

The AIO has one ADC for the 4 input channels, they are multiplexed. So they are samples at different times.
Mathias