Hioki RM3542, Instruction Manual, Page: 101 / 218

8.5 External Control Q&A
95
8
8.5 External Control Q&A
Common Questions Answers
How do I connect external trigger input?
Connect the (active low) TRIG input pin 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 outputs?
Both common ground pins can be shared by inputs and outputs.
How do I confirm output signals?
Confirm voltage waveforms with an oscilloscope. To do this, the output
pins such as EOM and comparator decision outputs need to be pulled up
(through several k

).
How do I troubleshoot input (control)
signal issues?
For example, if triggering 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 decision signals
retained during measurement (or can
they be off)?
The state is determined at the end of measurement, and is off once at the
start of measurement.
Why would the EOM signal not be
detected?
Try using the Pulse setting for EOM output.
When the measurement time is short and EOM output is set to Hold, the
time to de-assert may be too short to be detected by the PLC. When the
EOM output is set to Pulse, the signal is asserted (ON) for the specified
pulse width before turning off.
What situations cause measurement
faults to occur?
An error is displayed in the following cases:
•
A probe is not connected
•
A contact is unstable
•
A probe or measurement object is dirty or corroded
•
Measurement object resistance is much higher than the measurement
range
Is a connector or flat cable for connec-
tion provided?
A solder-type connector is supplied. The cable must be prepared at the
user's side.
Is direct connection to a PLC possible?
Direct connection is supported for relay or open-collector outputs and
positive-ground optocoupler inputs. (Before connecting, confirm that volt-
age and current ratings will not be exceeded.)
Can external I/O be used at the same
time as RS-232C or other communica-
tions?
After setting up communications, it is possible to control measurement
with the TRIG signal while acquiring measurement data via a communi-
cations 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?
Please use the free software for acquiring measured values available for
download from our website.