Digital Ports - Counters; Counters; Reset Mode; Accumulating Mode - Intab PC-Logger 2100 User Manual

4

DIGITAL PORTS - COUNTERS

The "2100" has, in addition to the 8 analogue inputs, three digital ports. These
ports, called P1, P2 and P3, have their main use in pulse-counting applications.
P1 can also be programmed as an output for alarm related purposes.
Pulse counting channels have channel numbers 25 to 27.
Digital inputs appear in channel 31 as one digital bit per input: P1=bit0,
P2=bit1, P3=bit2. The numeric value is the sum of the binary weights of the
three bits.
The digital output is reflected in channel 32. It has the value 0 for a non-active
output and 1 for an active output.
This rather strange channel numbering is the result of our effort to keep it
compatible with PC-loggers 3100i and 3150i.
4.1

Counters

Flow sensors that output an electric pulse for every unit volume that has passed it
are a perfect match for these inputs. By noting counter value and resetting it
every ∆t you get a very exact figure for flow.
Flow, as you well remember, is volume per time, or litres per ∆t, or litres per
minute or ...
Each counter can count up to 65535 then it wraps around and starts at 0 again.
You have to make ∆t short enough so that this doesn't happen.
The counters have two basic modes of operation: Reset mode and Accumulating
mode.

4.1.1 Reset mode

By "Reset mode" we mean the "flow measuring" mode mentioned above. The
counters are read and reset in the same operation every ∆t.
Counters appear as if they were analogue channels showing pulses (or litres or..)
per ∆t.

4.1.2 Accumulating mode

In Accumulating mode the counters are read every ∆t but not reset. The stored
value can then be looked upon as the integral from the time of the start of the
recording up to the "present".
4 DIGITAL PORTS - COUNTERS
Page 19