Description - Intab PC-Logger 3100i How To Use Manual

2

DESCRIPTION

Each constant current sources board may have 8, 16 or 24 constant current
outputs.
Every group of 8 sources is really only one source that is multiplexed in turn to
the eight outputs.
This means that the constant current is not flowing all the time. It is only present
and constant during the time its associated channel is being sampled.
Each channel takes between 80ms and 100ms to sample. The maximum time the
constant current is flowing is actually only this long. Therefore it never
contributes to any self-heating of the sensor.
What are the implications of what we have just said? well!
Channels are sampled one by one within an 8-group.
As channel one is sampled there is a constant current coming out of source #1.
As channel two is sampled there is a constant current coming out of source #2.
And so on.
Note that channel groups 9-16 and 17-24 are "in step" with the first group. I.e.
channel 9 and channel 17 are sampled concurrently with channel number one.
39
OPTION : Constant Current Sources