Enabling Real Time Plotting For Utms - Keithley 4200-SCS Reference Manual

Section 6: Keithley Interactive Test Environment (KITE)

Enabling real time plotting for UTMs

Since the release of KITE version 5.0, you can plot data in real time. The following explains how to
enable real time plotting in UTM.
Beginning with KTE version 5.0, there were three new functions added in the existing Linear
Parametric Test (LPT) library. Those are PostDataDouble(), PostDataInt(), and
PostDataString() respectively. The protocols of the three functions are listed as follows:
PostDataDouble(char *, double *)
PostDataInt(char *, int *)
PostDataString(char *, char *)
These functions are used right after one measurement point is finished and data value is assigned
to the corresponding output variable. They will transfer the data value from memory to the data
sheet in the UTM and plot it on the graph. PostDataDouble() is used to transfer a double type
data point from memory back to the data sheet. PostDataInt() is used to transfer an integer
type data point from memory back to the data sheet. PostDataString() is used to transfer a
string from memory back to the data sheet. Each function should be used according to type
defined for the corresponding output parameter. For example, if an output parameter is defined as
double, then PostDataDouble() function should be used to bring data back to the data sheet
and then plot it in real time.
The first parameter in the three functions is the variable name, defined as char *. For example, if
the output variable name is DrainI, then DrainI (with quotes) should be used in the first
parameter. The second parameter is the value of the variable to be transferred. For example, if
DrainI[10] should be transferred, then one should call PostDataDouble("DrainI",
DrainI[10]).
When using the new functions to transfer data into the data sheet in real time, make sure the data
is already located in the memory of the 4200-SCS. Sweep measurements are not suitable for real
time transfer because data is not ready until sweep finishes. The following examples show how to
enable real time plotting for a UTM.
1. I-V measurement using SMUs of a 4200-SCS
As mentioned above, if you need real-time plotting, the sweep type of measurement cannot
be used. Therefore, functions that are sweep related, such as smeasx(), sintgx(), and
sweepx(), cannot be used. Instead, create a for loop in the program to do point-by-point
measurement. Here is one example. In this example, SMU1 is used to force voltage and
then measure current. Programmed voltage and measured current are then outputted for
plotting.
Without real time plotting:
#include "keithley.h"
int IV(double startv, double stopv, int numpoint,
double * V, int Vsize, double * I, int Isize)
{
// error checking
if ((numpoint != Vsize) ||(numpoint != Isize))
return –1;
rtfary(V); // return force array of Voltage
sintgi(SMU1, I); // measure current
// setup sweep with 0.01 second sweep delay and
then trigger the measurement
sweepv(SMU1, startv,stopv,numpoint-1,0.01);
return (OK);
}
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Model 4200-SCS Reference Manual
4200-901-01 Rev. S / May 2017