User`s manual

52 www.rabbit.com RabbitFLEX BL300F Options
4.3.13 Analog-to-Digital Converters
The RabbitFLEX BL300F has a ramp-compare ADC. Up to 16 channels are available. The analog inputs
can be on any combination of pins 1 through 8 on both J3 and J4. The design of the ADCs allow you to
choose a current or voltage input on these pins. The measurement range options are:
• 0-3 V
• 0-10 V
• 4-20 mA
The ADCs work with single-ended unipolar voltage inputs and industry standard 4-20 mA current loops.
The digital result has an 8-bit resolution and the sampling frequency is determined by the following equa-
tion.
The ADC channels are sampled round-robin, so the sampling frequency depends on the number of analog-
to-digital channels that exist on the RabbitFLEX BL300F. If there is only one ADC, the sampling fre-
quency is about 425 samples per second. If the maximum of 16 ADCs exist, the sampling frequency is
about 25 samples per second.
The ADCs are not meant for applications that require very fast data acquisition rates. They are suitable for
measuring analog voltages that change slowly.
Sampling Frequency for ADCs
1000 ms
2.35 ms # A/D channels×
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