5.7. INSTrument

Each channel of the PSU is considered as separate (logical) instrument, which is required by the SCPI standard. The INSTrument subsystem provides a mechanism to identify and select instruments and establish coupling to simplify programming of more channels at once.

 

SCPI command

Description

INSTrument

 

[:SELect] {<channel>}

Selects the output to be programmed

:COUPle

 

:TRACking {<type>}

Selects independent, parallel-tracking, or series-tracking mode

:TRIGger {<mode>}

Selects a coupling between channels trigger systems

:DISPlay

 

:TRACe[<n>] {<value>}

Selects output value on the specified display trace

:SWAP

Swaps positions of selected output values

:YT

 

:RATE {<duration>}

Selects YT view sample duration

:NSELect {<channel>}

Selects the output to be programmed

5.7.1. INSTrument[:SELect]

Syntax

INSTrument[:SELect] {<channel>}

INSTrument[:SELect]?

Description

This command selects the output to be programmed by the output identifier. The outputs of the PSU are considered as two logical instruments. The INSTrument command provides a mechanism to identify and select an output.

When one output is selected, the other output is unavailable for programming until selected. The following commands are affected by the INSTrument command: SOURce, MEASure, and CALibration.

Parameters

Name

Type

Range

Default

<channel>

Discrete

CH1|CH2

Return

Query returns the currently selected output by the INSTrument[:SELect] or INSTrument:NSELect command. The returned value is CH1 or CH2.

Usage example

INST?

CH1

INST:SEL?

CH1

Related Commands

INSTrument:NSELect

5.7.2. INSTrument:COUPle:TRACking

Syntax

INSTrument:COUPle:TRACking {<type>}

INSTrument:COUPle:TRACking?

Description

This command selects how channel’s outputs will be internally connected:

  • independent (NONE)
  • parallel-tracking (PARallel) controls K_PAR power relay state when max. output current is doubled (e.g. 10 A instead of 5 A), or
  • series-tracking (SERies) that controls K_SER power relay state and max. output voltage is doubled (e.g. 80 V instead of 40 V).

When channels are coupled, resulting output will be present on different binding posts as indicated with LED_SP (red) instead of LED_OUT1 (green) and/or LED_OUT2 (green).

Coupled channels will be seen as single channel. Therefore the following commands will affect the both channel regardless of which channel is currently selected using the INSTrument[:SELect] or INSTrument:NSELect command):

  • OUTPut[:STATe], OUTPut:DPRog, OUTPut:PROTection:CLEar
  • MEASure[:SCALar]:CURRent[:DC], MEASure[:SCALar]:POWer[:DC], MEASure[:SCALar][:VOLTage][:DC]
  • SIMUlator:LOAD, SIMUlator:LOAD:STATe
  • [SOURce[<n>]]:CURRent, [SOURce[<n>]]:CURRent:STEP, [SOURce[<n>]]:CURRent:TRIGgered, [SOURce[<n>]]:CURRent:LIMit, [SOURce[<n>]]:CURRent:MODE, [SOURce[<n>]]:CURRent:PROTection:DELay, [SOURce[<n>]]:CURRent:PROTection:STATe, [SOURce[<n>]]:CURRent:PROTection:TRIPped?, [SOURce[<n>]]:LIST:COUNt, [SOURce[<n>]]:LIST:CURRent, [SOURce[<n>]]:LIST:DWELl, [SOURce[<n>]]:LIST:VOLTage[:LEVel], [SOURce[<n>]]:LRIPple, [SOURce[<n>]]:LRIPple:AUTO, [SOURce[<n>]]:POWer:LIMit, [SOURce[<n>]]:POWer:PROTection[:LEVel], [SOURce[<n>]]:POWer:PROTection:DELay[:TIME], [SOURce[<n>]]:POWer:PROTection:STATe, [SOURce[<n>]]:POWer:PROTection:TRIPped?, [SOURce[<n>]]:VOLTage, [SOURce[<n>]]:VOLTage:LIMit, [SOURce[<n>]]:VOLTage:STEP, [SOURce[<n>]]:VOLTage:TRIGgered, [SOURce[<n>]]:VOLTage:MODE, [SOURce[<n>]]:VOLTage:PROTection[:LEVel], [SOURce[<n>]]:VOLTage:PROTection:DELay, [SOURce[<n>]]:VOLTage:PROTection:STATe, [SOURce[<n>]]:VOLTage:PROTection:TRIPped?
  • TRIGger[:SEQuence][:IMMediate], TRIGger[:SEQuence]:DELay, TRIGger[:SEQuence]:SLOPe, TRIGger[:SEQuence]:SOURce

The following channel specific commands will generate a device specific error 312 when channels are coupled:

  • CALibrate,
  • OUTPut:TRACk[:STATe],
  • SIMUlator:RPOL, SIMUlator:VOLTage:PROGram,
  • [SOURce[<n>]]:LRIPple, [SOURce[<n>]]:LRIPple:AUTO
  • [SOURce[<n>]]:VOLTage:PROGram,
  • [SOURce:]VOLTage:SENSe (series-tracking only)

Channels coupled in parallel could have only one down-programmer circuit active that is on the channel 1. State of the channel 2 down-programmer will always be off regardless of what is set with the OUTPut:DPRog command.

 

If channels are calibrated (CAL:STAT? 1) a max. value of the channel that has lower calibrated value will be used as a reference and multiplied by two. For example, if channel 1 max. voltage is 39.98 and channel 2 max. voltage is 40.00 the new max. value for the SERies-tracking will become 79.96 V instead of 80.00 V.

 

Two conditions requires special attention: that is entering CC mode while channels are coupled in SERies or entering CV mode when PARallel coupling is active.

For example when coupled in SERies and output voltage is set to 60 V and current to 1.7 A with connected load of 1 Ω the PSU will enter the CC mode of operation (see OUTPut:MODE?) and output voltage will drop to 1.7 V. Coupling mechanism will set both channels to 30 V (inital value divided by two) but that value cannot be maintained on any output and there is no warranty that new voltage will be equally shared between channels (i.e. 1.7 / 2 = 1.35 V per channel). It’s even possible that outputs become unbalanced in a way that one of the channels becomes negative like -0.6 V on one channel and +2.3 V on another that still resulting in required +1.7 V limited by max. current. To avoid such situation coupling mechanism also include balancing to ensure that such deviation when one channel is pushed to sink instead of source power is rectified. That is accomplished by calculating and set more appropriate output voltage values during the CC mode of operation. The measured output voltage (using the MEASure[:SCALar][:VOLTage][:DC]? Command) will return that newly programmed value, that could be e.g. 30.93 V instead of 60 V. When output come back to CV mode of operation (e.g. load is disconnected), initial set 60 V will be measured again.

 

Execution of this command also affects bit 8 (PARAlell) or bit 9 (SERies) of the Operation status register (see Section 3.3).

 

At *RST, channels will be uncoupled (NONE).

Parameters

Name

Type

Range

Default

<type>

Discrete

NONE|PARallel|SERies

NONE

Return

Query returns the currently selected output coupling state.

Usage example

INST:COUP:TRAC SER

VOLT 70

VOLT?

70.00

INST:COUP:TRAC PAR

CURR 9

CURR?

9.00

Errors

312,"Cannot execute when the channels are coupled"

Related Commands

*SAV

MEASure[:SCALar]:CURRent[:DC]

MEASure[:SCALar][:VOLTage][:DC]

OUTPut:DPRog

OUTPut:MODE?

OUTPut:TRACk[:STATe]

5.7.3. INSTrument:DISPlay:TRACe[<n>]

Syntax

INSTrument:DISPlay:TRACe[<n>] {<value>}

INSTrument:DISPlay:TRACe[<n>]?

Description

This command sets the output value that will be displayed on the display position (trace) defined with [<n>]. This command affects only display modes 2, 3 and 4 (see the DISPlay:VIEW command).

An attempt to select the same value on both positions (traces) will generate an execution error.

Parameters

Name

Type

Range

Default

<value>

Discrete

VOLTage|CURRent|POWer

Return

Query returns the currently selected displayed output value on the selected display position (trace).

Usage example

INST:DISP:TRAC2?

CURR

Errors

-200,"Execution error"

Related Commands

DISPlay:VIEW

INSTrument:DISPlay:TRACe:SWAP

INSTrument:DISPlay:YT:RATE

5.7.4. INSTrument:DISPlay:TRACe:SWAP

Syntax

INSTrument:DISPlay:TRACe:SWAP

Description

Use this command to swap output values display positions.

Usage example

INST:DISP:TRAC1?

VOLT

INST:DISP:TRAC2?

CURR

INT:DISP:TRAC:SWAP

INST:DISP:TRAC1?

CURR

INST:DISP:TRAC2?

VOLT

Related Commands

DISPlay:VIEW

INSTrument:DISPlay:TRACe[<n>] {<value>}

INSTrument:DISPlay:YT:RATE

5.7.5. INSTrument:DISPlay:YT:RATE

Syntax

INSTrument:DISPlay:YT:RATE {<duration>}

INSTrument:DISPlay:YT:RATE?

Description

This command sets the sample duration in seconds when YT (mode 4, see the DISPlay:VIEW command) display view is selected.

Parameters

Name

Type

Range

Default

<duration>

Numeric (NR2)

0.02 – 300

0.1

Return

The query command returns the programmed sample duration in seconds.

Usage example

INST:DISP:YT:RATE 10

Related Commands

DISPlay:VIEW

INSTrument:DISPlay:TRACe[<n>] {<value>}

INSTrument:DISPlay:TRACe:SWAP

5.7.6. INSTrument:COUPle:TRIGger

Syntax

INSTrument:COUPle:TRIGger {<mode>}

INSTrument:COUPle:TRIGger?

Description

Not implemented yet

 

This command defines a coupling between channels trigger systems. Use ALL parameter to couple or NONE to remove coupling.

 

At *RST, trigger systems are uncoupled.

Parameters

Name

Type

Range

Default

<mode>

Discrete

NONE, ALL, CH1, CH2

ALL

Return

This query returns the currently coupled output.

Usage example

INST:SEL CH1

VOLT:TRIG 12

CURR:TRIG 1.5

INST:SEL CH2

VOLT:TRIG 5

CURR:TRIG MAX

INST:COUP:TRIG ALL

TRIG:SOUR IMM

INIT

Related Commands

*RST

INSTrument:COUPle:TRACking

5.7.7. INSTrument:NSELect

Syntax

INSTrument:NSELect {<channel>}

INSTrument:NSELect?

Description

This command is used in conjunction with the SELect command. It serves the same purpose, except that it uses a numeric value instead of the identifier used in the SELect command.

Parameters

Name

Type

Range

Default

<channel>

Numeric (NR1)

1|2

Return

When queried it returns the logical instrument number of the currently selected PSU channel. Note that the numbering used for logical instruments directly corresponds to the numbers used in status reporting for multiple instruments; specifically the STATus:QUEStionable:INSTrument and STATus:OPERation:INSTrument commands.

Usage example

INST:NSEL 2

INST:NSEL?

2

Related Commands

STATus:QUEStionable:INSTrument

STATus:OPERation:INSTrument