Measurement Computing Personal Daq rev.6.0 User Manual
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2-14 General Information & Specifications
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Personal Daq User’s Manual
In Personal Daq applications, thermocouples should not be connected single-ended. Doing
so can result in noise and false readings. This is especially true when acquiring other high-
amplitude signals in conjunction with thermocouple signals that are connected single-ended.
Personal Daq units include built-in cold-junction compensation (CJC), which is automatically invoked
when you select TC measurements. The Personal Daq automatically converts acquired voltage readings
into compensated-linearized temperature readings. A Personal Daq system can make thermocouple and
volts measurements concurrently.
Frequency/pulse These input channels can measure from DC to 1MHz. Readings can be in pulse count
(totalize), frequency, or duty cycle. Input voltage range is –15 to +15VDC, with the logic threshold at
<1.3V (low) and >3.8V (high). Frequency and pulse measurements can be scanned along with analog
input measurements with resolution up to 7 digits. Frequency low connections (Lo) are not to be confused
with the analog commons (COM). Frequency Los are located next to F1 and F3 channel connections. The
connection points labeled “Lo” serve as a common reference for frequency inputs.
Frequency/pulse
channels do not apply to Personal Daq/54.
Digital I/O You can program each digital I/O line individually as input or output. The digital I/O lines
do not make use of the Lo or COM connections. Digital output lines do make use of special digital return
lines designated by the letters RTN.
Digital I/O channels do not apply to Personal Daq/54.
Digital input lines can be read as part of the analog scan sequence and can be scanned over
100 times per second. Digital input voltage may range from 0 to +15V, with the logic threshold at
<1.3V (low) and >3.8V (high). Digital values outside of the 0 to +15V range are not permitted.
Digital output lines can be updated at any time prior to, or during an acquisition sequence; or can
be automatically updated over 100 times per second. Digital outputs share a common return
(RTN). In the output mode each output is an open-collector capable of sinking up to 150mA for
direct drive applications, and capable of pull-up voltages up to +15 VDC. Note that over-voltage
is rated at +20 VDC for up to 1 minute.