Keithley 2750 User Manual

Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-5
LSYNC (line cycle synchronization)
Synchronizing A/D conversions with the frequency of the power line increases common
mode and normal mode noise rejection. When line cycle synchronization is enabled, the
measurement is initiated at the first positive-going zero crossing of the power line cycle
after the trigger.
Figure 3-1 shows the measurement process that consists of two A/D conversions. If the
trigger occurs during the positive cycle of the power line (Trigger #1), the A/D conversion
starts with the positive-going zero crossing of the power line cycle. If the next trigger
(Trigger #2) occurs during the negative cycle, then the measurement process also starts
with the positive-going zero crossing.
Figure 3-1
Line cycle synchronization
Perform the following steps to enable or disable line cycle synchronization:
1. Press SHIFT and then LSYNC to display the present state of line synchronization
(OFF or ON).
2. Use the up or down key to display “LINESYNC ON” or “LINESYNC OFF.”
3. Press ENTER. The instrument returns to the normal display state.
NOTE Line synchronization is not available for the AC functions (ACV, ACI, FREQ, or
PERIOD), and for integration rates <1 PLC, regardless of the LSYNC setting.
1 PLC
A/D
Conversion
A/D
Conversion
Trigger
# 1
Trigger
# 2
Reading
Done
Reading
Done
2750-900-01.book Page 5 Wednesday, August 3, 2011 7:56 AM

Keithley 2750 Specifications

General

Interface	GPIB, RS-232, Ethernet
Switching Speed	Up to 500 channels/second
Maximum Voltage	300V
Operating Temperature	0°C to 50°C
Measurement Functions	DCV, ACV, DCI, ACI, 2-wire Resistance, 4-wire Resistance, Frequency, Temperature
Resolution	6.5 digits
Current	1A
Maximum Current	1A