[SENSe:]TEMPerature:TRANsducer:FRTD:REFerence
Syntax
[SENSe:]TEMPerature:TRANsducer:FRTD:REFerence <mode> [, (@<ch_list>)]
[SENSe:]TEMPerature:TRANsducer:FRTD:REFerence? [(@<ch_list>)]
Description
This command disables or enables the specified 4-wire RTD channels to be used as the reference channel for subsequent thermocouple measurements that specify an external reference source (see [SENSe:]TEMPerature:TRANsducer:TCouple:RJUNction:TYPE command). If you omit the optional <ch_list> parameter, this command applies to the internal DMM, independent of any channels or a scan list.
Used With:
34921A Armature Multiplexer (with optional 34921T Terminal Block)
34922A Armature Multiplexer
34923A Reed Multiplexer (differential mode only)
34924A Reed Multiplexer
Parameters
|
Name |
Type |
Range of Values |
Default Value |
|
<mode> |
Boolean |
{OFF|0|ON|1} |
OFF |
|
<ch_list> |
Numeric |
One or more channels in the form (@sccc). |
If <ch_list> is omitted, this command applies to the internal DMM. |
Remarks
If you omit the optional <ch_list> parameter, the configuration applies to the internal DMM, independent of any channels or a scan list (any existing scan list is not redefined). An error is generated if the internal DMM is not installed or is disabled.
Since 2-wire and 4-wire resistance are related functions, changing a measurement parameter for one function will also change the corresponding parameter for the other function (see [SENSe:]TEMPerature:TRANsducer:RTD:REFerence command).
For 4-wire RTD measurements, the instrument automatically pairs channel n in Bank 1 with channel n+20 in Bank 2 (34921A, 34923A) or n+35 (34922A, 34924A) to provide the source and sense connections. For example, make the source connections to the HI and LO terminals on channel 2 in Bank 1 and the sense connections to the HI and LO terminals on channel 22 (or 37) in Bank 2. Specify the paired channel in Bank 1 (source) as the <ch_list> channel (channels in Bank 2 are not allowed in the <ch_list>).
When you initiate a measurement on the selected channels (see INITiate or READ? command), the acquired temperature is stored in volatile memory in the reference register. Subsequent thermocouple measurements use the stored temperature as their reference.
At power-on, the reference register is loaded with "9.9E+37". Note that until you store a reference temperature, all thermocouple measurements that specify an external reference source will be returned as "9.9E+37". Use the [SENSe:]TEMPerature:TRANsducer:TCouple:RJUNction:EXTernal? command to read the most-recently stored reference temperature value.
The reference temperature can also be stored using a thermistor measurement. See the [SENSe:]TEMPerature:TRANsducer:THERmistor:REFerence command for more information.
Return Format
The query command returns "0" (OFF) or "1" (ON) for each channel specified. Multiple responses are separated by commas.
Examples
Example 1: Making Externally-Referenced Thermocouple Measurements with Multiplexer Channels
The following commands configure multiplexer channel 3 in slot 1 for thermocouple measurements and select an external reference junction for that channel.
CONF:TEMP TC,J,(@1003)
TEMP:TRAN:TC:RJUN:TYPE EXT,(@1003)
The following commands configure multiplexer channel 1 in slot 1 for 4-wire RTD measurements and assign this channel as the reference channel. For this 4-wire measurement, the instrument automatically pairs this channel in Bank 1 with the corresponding channel in Bank 2.
CONF:TEMP FRTD,85,(@1001)
TEMP:TRAN:FRTD:REF ON,(@1001)
The following commands set up a scan list that contains both the reference channel (channel 1) and the thermocouple channel (channel 3). If you do not include the reference channel in the active scan list, the instrument uses the temperature previously stored in the reference register. The INITiate command initiates the scan.
ROUT:SCAN (@1001:1005)
INIT
Example 2: Making Externally-Referenced Thermocouple Measurements with the Internal DMM
The following commands configure the internal DMM (no <ch_list> specified) for 4-wire RTD measurements and assign the internal DMM as the reference "channel".
CONF:TEMP FRTD,85
TEMP:TRAN:FRTD:REF ON
The following command initiates an RTD measurement on the internal DMM and stores the value in the reference register.
INIT
The following commands configure the internal DMM for thermocouple measurements and select an external reference junction.
CONF:TEMP TC,J
TEMP:TRAN:TC:RJUN:TYPE EXT
The following commands change the sample count to take 10 thermocouple measurements and initiate the internal DMM.
SAMP:COUN 10
INIT
Example 3: Querying the Reference Channel State
The following command returns the state of reference channel 3 in slot 1.
TEMP:TRAN:FRTD:REF? (@1003)
Typical Response: 1
See Also
[SENSe:]TEMPerature:TRANsducer:TCouple:RJUNction:EXTernal?