14.1 Troubleshooting
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External Control (EXT I/O) Q&A
Common Questions Answers
How do I connect external trigger
input?
Connect the TRIG signal to an ISO_COM pin using a switch
or open-collector output.
Which pins are common ground for
input and output signals?
The ISO_COM pins.
Are the common (signal ground)
pins shared by both inputs and out-
puts?
Use ISO_COM as the common pin for input and output sig-
nals. The ISO_COM pin serves as the shared common pin.
How do I confirm output signals?
Confirm voltage waveforms with an oscilloscope. To do this,
the output pins such as EOM and comparator judgment out-
puts need to be pulled up (through several k).
How do I troubleshoot input (con-
trol) signal issues?
For example, if TRIG signal does not operate properly,
bypass the PLC and short the TRIG pin directly to an
ISO_COM pin. Be careful to avoid power shorts.
Are the comparator judgment sig-
nals retained during measurement
(or can they be off)?
When using the external trigger [EXT] setting, the state is
determined at the end of measurement, and is off once at
the start of measurement. When using the internal trigger
[INT] setting, judgment results are held during measure-
ment.
What situations cause measure-
ment faults to occur?
An error is displayed in the following cases:
• A probe is not connected
• A contact is unstable
• A probe or measurement target is dirty or corroded
• Measurement target resistance is much higher than the
measurement range
Is a connector or flat cable for con-
nection provided?
A solder-type connector is supplied. The cable must be pre-
pared at the user's side.
Is direct connection to a PLC possi-
ble?
If the PLC’s outputs are relays or open collectors and the
PLC’s input circuit supports contact input, it can be con-
nected directly. (Before connecting, confirm that voltage
and current ratings will not be exceeded.)
Can external I/O be used at the
same time as RS-232C or other
communications?
After setting up communications, it is possible to control
measurement with the TRIG signal while acquiring mea-
surement data via a communications interface.
How should external power be con-
nected?
The instrument's external I/O input and output signals all
operate from an internal isolated power source, so power
must not be supplied from the PLC side.
Can free-running measured values
be acquired using a footswitch?
Measured values can be acquired using the sample appli-
cation. The sample application can be downloaded from the
Hioki website (http://www.hioki.com).
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