EDIT PROBE
soft-key in the
PROBE
menu (see Section 5.2.1). The coeffi-
cient values are normally provided with the probe on a calibration report. Be
sure to select the proper equation type, R(T) or T(R).
11.3.4
Current
The 2564 sources current to the sensor and measures the resulting voltage
across the sensor to determine its resistance. The current alternates every 0.5
seconds to reduce the effects of thermoelectric offsets. The current automati-
cally switches between 2
μ
A and 10
μ
A depending on the resistance being
measured. At lower resistances (below about 50 k
Ω
) 10
μ
A is used. At higher
resistances 2
μ
A is used. You can force the current source to use 2
μ
A for low
resistances if necessary using the
SET UP DEVICE
function in the
MODULE
menu (see Section 5.4.2). Change the CURRENT parameter from AUTO to 2.0
and press
ENTER
.
The
SET UP DEVICE
function also allows access to two other parameters.
SAMP PER selects the sample period between 2 (normal) and 10 seconds. RES
RANGE sets the resistance range between AUTO ranging (normal), LOW
range, and HIGH range. The purpose of these options is mainly for trouble-
shooting and they should not need to be changed during normal operation.
11.3.5
Device Setup Commands
The SYST:MODn:DEVn:READ? and SYST: MODn:DEVn:WRIT commands
(see Sections 6.5.8.19 and 6.5.8.20) can be used to read or set the setup param-
eters for the 2564 Thermistor Scanner Module. The device number of the
Thermistor Scanner Input Device is 1. The module number for the 2564 mod-
ule is its position in the stack. For example, if the 1560 has four add-on mod-
ules, the 2564 being second, the module number for the 2564 is 2. Table 27
shows the device commands used to read or set the setup parameters of the
Thermistor Scanner Input Device.
Below are some examples of using the device commands to set the device setup
parameters. For these examples it is assumed that the 2563 Thermistor Scanner
Module is placed second 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.
1560 Thermometer Readout
User’s Guide
142
