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Logic states:
Input - High state
DC or AC voltage with an amplitude between Vmin & Vmax
Input - Low state
no voltage
Output - High state
*closed contact
Output - Low state
*open contact
*Note: these can be reversed by altering the position of links on the PLC card.
25VDC output:
This is provided to drive the PLC inputs/outputs, and is rated at 1.25 ADC. (For the
DO5001 model, it is only available when the instrument is connected to the mains,
and is not supplied by the internal batteries).
Measurement time:
For a basic resistance measurement, the approximate time from the rising edge of the
MEASURE line to the EOT (end of test) signal is:
Slow mode
700 mS
Medium mode
450 mS
Fast mode
240 mS
5.5 Description of Input/Output signals
Inputs:
COM IN
Common line for all inputs.
CTRLIN
Requests remote control of the microhmmeter, and locks
the keyboard. When released, control will revert to the front
panel.
N0-N3
Binary-coded data inputs for selection of set-up memories:
N3 N2 N1 N0
Memory No.
0
0
0
0
0
0
0
0
1
1
0
0
1
0
2
:
:
:
:
:
1
0
0
1
9
MEASURE
Triggers a measurement. If closed momentarily, a single
measurement will result. If left permanently closed,
continuous measurements will result.
Outputs:
The links on the PLC card are factory fitted such that the relay contacts will close
when an output signal is asserted, These can be reversed if required.
COM OUT
Common line for all outputs.
ACK
This signal acknowledges the CTRLIN signal, but not until
the first MEASURE input is received. It then remains
asserted as long as CTRLIN is asserted.
