Measurement Computing TempScan/1100 - Manual (Page 235)

TempScan / MultiScan User’s Manual 889897 API Command Reference A-39
J
- Calibrate Cold Junction Offset
TYPE Calibration
EXECUTION Immediate
SYNTAX Jchan,
type,
temp
Calibrate the cold-junction offsets for cold-junction compensation of the
thermocouple signals where chan is the channel number such that 1 <
chan < max , where max = 992 for the TempScan/1100 and max = 744
for the MultiScan/1200.
type is the thermocouple channel type.
temp is the reference temperature currently being applied to the selected
channel, with the form nnn.n in degrees º C.
DESCRIPTION
Note: This command is only for advanced users who perform their own calibration. It is not necessary
for normal, everyday operation.
Active only in Calibration Mode, the Calibrate Cold Junction Offset ( J ) command is used to calibrate the cold
junction offsets for cold-junction compensation of the thermocouple signals. Each thermocouple input channel
has associated with it one of these temperature sensors. Although calibrated at the factory, these temperature
sensors are subject to component aging which may affect their accuracy over time. The function of the
J
command is to allow the adjusting of the internal firmware to compensate for the affects of component aging.
Since there are 4 cold junction temperature sensors associated with 32 temperature input channels, it is
necessary to select 4 channels. Each channel is associated with one of the 4 cold junction temperature sensors
in order to calibrate all cold junction temperature sensors on a given card.
For more information on manual calibration, see chapter System Calibration.
Note: To achieve correct results, four separate channels on each card must be supplied with an accurate
thermocouple signal of known warm junction temperature before performing this command. After the
command has been issued, the applied thermocouple signal must remain at its value until the TRIGGER
LED indicator stops flashing.
Note: The parameter type is the same channel type that is used with the Configure Channels (C) command.
EXAMPLE
PRINT#1, “OUTPUT07;K12345X” ‘ Enter Calibration Mode
‘ Apply precision temperature
PRINT#1, “OUTPUT07;J812,2,101.7X” ‘ Compute cold junction offset for the temperature
sensor associated with the type K thermocouple
on channel 1 of slave card 25 at 101.7
°C
‘ Wait for command to complete
‘ Remove precision temperature
PRINT#1, “OUTPUT07;EX” ‘ End Calibration Mode