LabJack U12 User manual

Analyser AutoSPY®1
Analyser AutoSPY
Quick Guide to A/D Measuring Device LabJack U12
With the A/D measuring device LabJack U12 you can record up to 8 analog and 20 digital electric
signals in AutoSPY, for instance from switches, light barriers, temperature or pressure sensors. That
allows trouble shooting and optimization to cover electrical signals that are not available in a PLC
directly or that shall be double-checked by independent measurements.
The LabJack can easily be attached to the USB port of the analysis PC and does not require any addi-
tional power supply. Windows comes with the required drivers preinstalled, such that AutoSPY can
instantly access the LabJack. Multiple LabJacks can be operated at different USB ports and recorded
at the same time in AutoSPY, if you need to measure more signals than a single unit can handle.
Specification of Measurement Inputs
Analog inputs AI0 through AI7
The LabJack has eight screw terminals AI0 through AI7 for analog input signals. These can measure
voltages up to ± 10 V with respect to ground (GND) with a resolution of 12 bit / 4.88 mV. To do so, at
first the ground and afterwards the signal line need to be connected to the corresponding terminals.
Beside this so called single-ended measurement, the LabJack is capable of measuring the input pairs
AI0/1, AI2/3, AI4/5 and AI6/7 in differential mode. As stated in the following table, each of these four
differential channels can provide a gain of up to 20 to achieve a higher effective measurement resolu-
tion for smaller voltage ranges.
Gain G Maximum voltage
between AI and GND
Maximum differential
voltage
Measurement resolution
1
± 10 V
± 20 V
4.88 mV
2
± 5 V
± 10 V
2.44 mV
4
± 2.5 V
± 5 V
1.22 mV
5
± 2 V
± 4 V
0.98 mV
8
± 1.25 V
± 2.5 V
0.61 mV
10
± 1 V
± 2 V
0.49 mV
16
± 0.625 V
± 1.25 V
0.31 mV
20
± 0.5 V
± 1 V
0.24 mV
A/D measurement
unit LabJack U12
Digital extension module CB25

Analyser AutoSPY®2
As in single-ended mode, the ground terminal (GND) should be connected with the ground of the
circuit to be tested. The voltage of each AI with respect to ground must not exceed the values stated in
the table, in order to achieve correct measurement results. The maximum differential voltage (with a
gain of G = 1 this is 20 V for instance) occurs, when one input carries the maximum (+10 V with
G = 1) and the other input carries the minimum voltage (-10 V with G = 1).
Note:Both measurement modes can be combined. Regardless of the configured measurement
mode or gain, voltages beyond ± 40 V must not be attached to any of the LabJack’s
analog inputs, in order to avoid physical damage to the device. However, this is solely a
rule to prevent damage. Voltages that exceed the limits stated in the table will be capped
to the minimal or maximal limit, respectively.
Digital inputs IO0 through IO3 and D0 through D15
The LabJack provides 20 digital inputs in total (LOW < 0.8 V; HIGH > 4 V). Four of these, referred to
as IO0 through IO3, can be connected at the right terminal block. The remaining ones, referred to as
D0 through D15, can be accessed via the DB25 connector at the narrow side of the LabJack or the
CB25 extension module that can be attached there.
Pinout of the DB25 extension
D-sub connector:
Important: The four inputs IO0 through IO3 can be fed with voltages up to 15 V. Signals exceeding
this range (e. g. typical PLC signals) necessarily require an adequate protective circuit,
like the following voltage divider:
The 16 inputs D0 through D15, as they are accessible through the extension connector, are designed
for TTL signals only, and do not provide any overvoltage or short-circuit protection. The CB25 exten-
sion module, however, provides additional protection, such that voltages between -20 V and +25 V
can be connected. In this case you must not install the jumpers that bypass the protection resistors on
the CB25 board!
Note:The three inputs D13 through D15 are Schmitt trigger inputs. They transit from LOW to
HIGH on an input voltage of about 2.7 V and transit back from HIGH to LOW on an
input voltage of 1.5 V. If one of these input lines carries a voltage above 9.5 V, all three
inputs transit to HIGH, caused by the LabJack’s internal wiring.
Counter Input CNT
The LabJack provides a 32 bit counter that can be connected at screw terminal CNT. The counter is
incremented when it detects a falling edge (from >4 V to <1 V) followed by a rising edge. Thus, re-
setting the counter while the attached signal is LOW will cause the first rising edge not to be counted.
The connected voltage must not exceed +15 V in order to avoid damage to the LabJack. If necessary,
use the voltage divider circuit suggested above to protect the input. The counter can be configured to
operate in continuous mode to count piece numbers and the like, or it can be configured to reset after
each measurement to count revolutions, for instance.
1
D0
6
D5
11
+5V
16
GND
21
D11
2
D1
7
D6
12
+5V
17
GND
22
D12
3
D2
8
D7
13
+5V
18
D8
23
D13
4
D3
9
(NC)
14
GND
19
D9
24
D14
5
D4
10
+5V
15
GND
20
D10
25
D15

Analyser AutoSPY®3
Recording Data with AutoSPY
In order to record data from a LabJack in AutoSPY, a data source of that type must be inserted into the
document. Afterwards, the LabJack to be used for recording must be selected in the configuration
dialog of the newly created data source. The button “Identify” causes the status LED of the selected
LabJack to blink, which is useful when multiple LabJacks are attached to the same PC.
The tab “Signals” provides a graphical representation of the LabJack‘s screw terminals, where the
inputs to be recorded can intuitively be checked. Furthermore, the option “diff.” enables differential
measurement for analog inputs, which additionally allows for specifying a voltage range (which trans-
lates into the appropriate gain, internally) for higher measurement resolution.
This is all mandatory configuration work that is required for simple use cases. You can now connect to
your LabJack and start recording.

AutoSPY © 2019 TraceTronic GmbH
The tab “Options” allows further configuration to achieve higher sampling rates or enable special
features like triggering. The most important setting is the choice between one of the three recording
modes described below.
Recording Modes of the LabJack
By default the recording mode Polling is preset. This mode allows for recording all of the LabJack’s
signals, but they are not necessarily sampled simultaneously or in constant intervals. The sampling rate
depends on the particular mix of selected signals. Some benchmarks are given in the following table:
Signals to record
Sampling rate [samples / s]
Sampling interval [ms]
4 x AI, 4 x IO
62
16
4 x IO, CNT, 16 x D
62
16
4 x AI, 4 x IO, CNT, 16 x D
31
32
8 x AI, 4 x IO, CNT, 16 x D (all)
19
52
The mode Stream suits well for continuous recordings with maximum sampling rates. It supports re-
cording of up to four analog inputs together with the four digital inputs IO0 through IO3, but none of
the signals CNT and D0 through D15. Measurements of the analog inputs are taken with a constant
overall sampling rate between 200 and 1200 samples / s (which corresponds to sampling intervals
between 0.8 and 5.0 ms). Overall sampling rate means the count of analog measurements carried out
per second. Recording two analog inputs, for instance, is possible with up to 600 samples / s in stream
mode. The count of selected digital signals IO0 through IO3 has no impact on the sampling rate.
The mode Burst is subject to the same limitations as the Stream mode in terms of supported signals,
which means it supports up to four analog signals and the digital inputs IO0 through I03, but none of
the signals CNT or D0 through D15. However, the Burst mode can reach much higher overall sam-
pling rates between 1200 and 8192 samples / s (which corresponds to sampling intervals between 0.1
and 0.8 ms), but limits the length of continuous recording to 4096 analog samples. Afterwards, the
trace file will contain a small gap before recording is restarted automatically. Despite that limitation,
precise recording can be controlled by defining one of the digital inputs IO0 or IO1 as a trigger, which
causes the recording not to start until the trigger signal carries HIGH.