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Keithley 2000 scan module switch speed

KUSB and KPCI DAQ Data Acquisition Products
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Joined: August 26th, 2015, 2:48 am
Country: Denmark

Keithley 2000 scan module switch speed

Post by k_bonderup » August 26th, 2015, 2:59 am


I am using a Keithley 2010 together with a 10 channel scan module to monitor three DC voltage sources.
The example resembles the one from the 2010 manual (p.242-243) see below.

The count is placed on 3 and therefore the channels from 1 to 3. 10 sets are recorded with a 15 sec delay placed between the sets. However, what is the delay between channels in a single set (from @1 to @2 etc.) ? Can this delay be specified to a fixed number, e.g. 5ms ?

Thanks in advance.

CALL SEND(16, "*rst", status%)

CALL SEND(16, "stat:pres;*cls", status%)
CALL SEND(16, "stat:meas:enab 512", status%)
CALL SEND(16, "*sre 1", status%)

CALL SEND(16, "samp:coun 3", status%)
CALL SEND(16, "trig:sour tim;tim 15", status%)

CALL SEND(16, "trig:coun 10", status%)

CALL SEND(16, "trac:poin 30," status%)
CALL SEND(16, "trac:feed sens1;feed:cont next", status%)

CALL SEND(16, "rout:scan (@1:3)", status%)
CALL SEND(16, "rout:scan:lsel int", status%)

CALL SEND(16, "init", status%)

Dale C
Keithley Applications
Keithley Applications
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Joined: June 10th, 2010, 6:22 am
Country: United States

Re: Keithley 2000 scan module switch speed

Post by Dale C » August 26th, 2015, 6:00 am

Several parameters affect the measurement rate on the Model 2010.
1. Integration Rate - NPLC, this is part of the A/D conversion process. This is the time the unit "looks" at the input signal. It is configured in PLCs (Power Line Cycles). 1 PLC is 16.167msec of 60Hz and 20msec for 50Hz. the range is 0.01 to 10 PLC.
2. Ranging- Autorange slows things down as it takes time to figure out the appropriate range. Manual ranging is preferred for fast measurements.
3. Filter - This is a digital filter. And therefore slows things down.
4. Autozero - This helps the A/D conversion process go through all of its four phases (Signal Integrate, Zero Integrate, Reference Integrate and Calculate. Disabling autozero then the A/D process goes through signal integrate and calculate, this increases the measurement rate.
5. Trigger Delay - this is either Auto or manual. Select manual for fast responses.
6. Display - The display can be disabled for fast measurements.

All six of these parameters affect the measurement rate.
If you want to go fast then disable all of them and set NPLC to 0.01.
The maximum scan rate is about 110 switches per second.
The Measurement is on top of this rate. So the absolute maximum switch/read rate is about 100 per second.
Hope this helps.

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