Module is placed third in the stack. These commands can be sent through any
communication interface including the IEEE-488 and RS-232 interfaces.
SYST:MOD2:DEV1:WRIT “CURR”,2
Set the excitation current to 2
μ
A.
SYST:MOD2:DEV1:READ? “CURR”
Read the excitation current.
10.4
Calibration
This section explains the calibration procedure for the 2563 Thermistor
Module.
10.4.1
Calibration Parameters
The resistance measurement is derived from the ratio between the voltage mea-
surements of the input resistor and reference resistor (20 k
Ω
) using the follow-
ing equation.
resistance
K
ADJ
ratio
=
⋅
×
−
+
−
[ .
(
_
)( .
)
.
.
1111 10
2 0
10
1
6
100
0
1 0 10
2 0
1 0
1 0
4
][( .
_
) .
_
( .
.
)]
⋅
+
+
−
10
0
K
ADJ
ratio
ADJ
ratio
Three adjustable parameters are used for calibration:
0_ADJ
,
10K_ADJ
, and
100K_ADJ
.
0_ADJ
directly affects the measurement at 0
Ω
. It has negligible ef-
fect at 10 k
Ω
but significant affect at higher resistances.
10K_ADJ
directly af-
fects the measurement at 10 k
Ω
. It has negligible effect at 0
Ω
and
proportionately greater effect the higher the resistance.
100K_ADJ
directly af-
fects the measurement at 100 k
Ω
. It has negligible effect at 0
Ω
and 10 k
Ω
with
greater effect the more the resistance deviates from 0
Ω
or 10 k
Ω
. Each of the
parameters has positive effect at their primary resistances: increasing the value
of the parameter increases the measured resistance. The default and theoreti-
cally normal value for each is 0.
10.4.2
Front-panel Access
The calibration parameters
0_ADJ
,
10K_ADJ
, and
100K_ADJ
can be adjusted
to optimize the accuracy. They can be accessed from the front panel of the 1560
using the
CAL DEVICE
soft-key function. This is found in the
MODULE
sub-menu. Pressing the
CAL DEVICE
soft-key shows a list of devices with
the module position number. Use the
UD
buttons to move the cursor to the
STHR module and press
ENTER
.
1560 Thermometer Readout
User’s Guide
136
