CAL:STORE TARE
Optional depending on necessity of long
term storage.
CALibration:TARE
CALibration:TARE (@<
ch_list
>)
measures offset (or tare) voltage present on the
channels specified and stores the value in on-board RAM as a calibration constant
for those channels. Future measurements made with these channels will be
compensated by the amount of the tare value. Use
CALibration:TARE
to compensate
for voltage offsets in system wiring and residual sensor offsets. Where tare values
need to be retained for long periods, they can be stored in the module’s Flash
Memory (Electrically Erasable Programmable Read Only Memory) by executing
the
CALibration:STORe TARE
command. For more information see
“ Compensating for System Offsets” on page 138.
Important Note
for
Thermocouples
•
You must not use
CALibration:TARE
on field wiring that is made up of
thermocouple wire. The voltage that a thermocouple wire pair generates cannot
be removed by introducing a short anywhere between its junction and its
connection to an isothermal panel (either the HP E1313/E1413’s terminal module
or a remote isothermal reference block). Thermal voltage is generated along the
entire length of a thermocouple pair where there is any temperature gradient along
that length. To
CALibration:TARE
thermocouple wire this way would introduce
an unwanted offset in the voltage/temperature relationship for that thermocouple.
If you inadvertently
CALibration:TARE
a thermocouple wire pair, see “ Resetting
CALibration:TARE” on page 139.
•
You should use
CALibration:TARE
to compensate wiring offsets (copper wire, not
thermocouple wire) between the HP E1313/E1413 and a remote thermocouple
reference block. Disconnect the thermocouples and introduce copper shorting
wires between each channel’s HI and LO, then execute
CALibration:TARE
for
these channels.
Parameters
Parameter
Name
Parameter
Type
Range of
Values
Default
Units
<
ch_list
>
channel list (string)
100 - 163
none
Comments
•
CALibration:TARE
also performs the equivalent of a
*CAL?
operation. This operation
uses the Tare constants to set a DAC which will remove each channel offset as
“ seen” by the module’s A/D converter. As an example, assume that the system
wiring to channel 0 generates a +0.1 Volt offset with 0 Volts (a short) applied at the
Unit Under Test (UUT). Before
CALibration:TARE
, the module would return a
reading of 0.1 Volts for channel 0. After
CALibration:TARE (@100)
, the module will
return a reading of 0 Volts with a short applied at the UUT and the system wiring
offset will be removed from all measurements of the signal to channel 0.
CALibration
Chapter 5
HP E1313/E1413 Command Reference 181
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