LCLS-II LLRF Naming Conventions

Names are broken down into the standard parts, DeviceType : Area : Position : Attribute

Device Type

Name	Description
ACCL	Used for everything in the RF system that is part of the general physics and operations interface at the cavity level
GUN	Used for everything in the gun

Area, Subset of Accelerator With RF Devices

See https://slacspace.slac.stanford.edu/sites/lcls/lcls-2/wd/dsg/Forms/AllItems.aspx, Naming Convention section 6.1.2.2

Area	Physical Location
GUNB	LCLS-II Gun
L0B	LCLS-II L0 Accelerator Region
L1B	LCLS-II L1 Accelerator Region
BC1B	LCLS-II Bunch Compressor 1
L2B	LCLS-II L2 Accelerator Region
BC2B	LCLS-II Bunch Compressor 2
L3B	LCLS-II L3 Accelerator Region
SYS2	Full LCLS-II Accelerator scope, e.g. global phase offset

Position

See https://slacspace.slac.stanford.edu/sites/lcls/lcls-2/wd/dsg/Forms/AllItems.aspx, Naming Convention section 6.1.2.3.2

The position of the gun is 100. The position of the buncher is 455.

The position of a superconducting cavity is 4 numbers where the first two indicate the cryomodule and the second two the cavity. For example, 0430 is cryomodule 4, cavity 3.

Each cryomodule has 8 cavities. Cavities 1-4 are instrumented in LLRF Rack A. Cavities 5-8 are instrumented in LLRF Rack B.

Cryo Module #	Description
01-35	CM01-CM35, 1.3GHz cavity
H1	3.9GHz Cryomodule 1, located in L1B and follows CM03
H2	3.9GHz Cryomodule 2, located in L1B and follows H1

Numbering of cavities within a cryomodule:

Attribute

Attributes that comprise the physics interface. Scalar unless otherwise specified

R/W

Name

Description

SRF Example

(CM 2 Cavity 1)

Gun/Buncher Example

R/W

RFMODECTRL

RF mode control (SEL, SELA, SELAP, SEL Raw, Pulse, Chirp)

ACCL:L1B:0210:RFMODECTRL

N/A

R

RFMODE

Readback of current RF mode (SEL, SELA, SELAP, SEL Raw, Pulse, Chirp)

ACCL:L1B:0210:RFMODE

R/W

RFCTRL

Cavity on/off control. Off = LLRF drive set to 0. (SSA control will be different.)

ACCL:L1B:0210:RFCTRL

R

RFSTATE

Readback of cavity RF on/off state

ACCL:L1B:0210:RFSTATE

N/A

R/W

ADES

Operation amplitude setpoint (MV)

ACCL:L1B:0210:ADES

R

GDES

Gradient setpoint (MV/m) - readback only

ACCL:L1B:0210:GDES

N/A

R

AACT

Measured amplitude from cavity probe (MV)

ACCL:L1B:0210:AACT

R

GACT

Measured gradient from cavity probe (MV/m)

ACCL:L1B:0210:GACT

R/W

AMAX

Maximum allowable amplitude (MV) - experts only

ACCL:L1B:0210:AMAX

R

GMAX

Maximum allowable gradient (MV/m) - readback only

ACCL:L1B:0210:GMAX

R/W

PDES

Operation phase setpoint (degrees, where 0 is on-crest)

ACCL:L1B:0210:PDES

R

PACT

Measured phase from cavity probe (degrees)

ACCL:L1B:0210:PACT

R/W

PREF

a.k.a.gold, phase offset used by LLRF to convert measured phase to one relative to on-crest operation, adjusted by beam phasing (degrees)

ACCL:L1B:0210:PREF

R/W

SEL_POFF

SEL phase offset setpoint (not used in SELA/GDR mode)

ACCL:L1B:0210:SEL_POFF

N/A

R

SEL_POFF_RBV

SEL phase offset (not used in SELA/GDR mode)

ACCL:L1B:0210:SEL_POFF_RBV

N/A

R

DFACT

Measured etune frequency (Hz)

N/A

R

DF

Measured detune frequency (Hz) using state space equation, cavity and forward signals - used to drive piezos

ACCL:L1B:0210:DF

N/A

R

DF_FC

Measured detune frequency (Hz) using frequency counter method - not used in resonance control, larger operating range than DF

ACCL:L1B:0210:DF_FC

N/A

R

CHIRP:DF

Measured detune frequency (Hz) using chirp method - only active in Chirp and Pulsed modes, primarily for use when cavity is many kHz out of tune, operating range of tens of kHz or more

ACCL:L1B:0210:CHIRP:DF

N/A

R

AWF

Waveform of cavity probe amplitude, which is used to calculate AACT (MV)

R

PWF

Waveform of cavity probe phase, which is used to calculate PACT (degrees)

R

FWD

Forward signal from SSA to cavity - amplitude

R

FWDPWR

Forward signal from SSA to cavity - power

R

REV

Reverse signal from cavity - amplitude

R

REVPWR

Reverse signal from cavity - power

R/W

ALEM

LEM computed integrated RF amplitude (MV) per cavity and per cryomodule

ACCL:L1B:0210:ALEM

R/W

PLEM

LEM computed phase (deg)

ACCL:L1B:0210:PLEM

R/W

EGLEM

LEM computed energy gain (MeV)

ACCL:L1B:0210:EGLEM

R/W

CHLEM

LEM computed chirp (MeV)

ACCL:L1B:0210:CHLEM

R/W

CAV:FUDG

Beam-based scale factor applied to cavity probe amplitude readback. Nominal value of 1.

ACCL:L1B:0210:CAV:FUDG

R

L

Cavity design length - constant

ACCL:L1B:0210:L

N/A

R

FREQ

Cavity design frequency - constant

ACCL:L1B:0210:FREQ

N/A

R

IMPED

Cavity design shunt impedance - constant

ACCL:L1B:0210:IMPED

N/A

In Progress/Tentative

RFREADY

Status of RF controls, (Ready, Not Ready) set to ready when control loops are closed and RF is continuous. Or will we ever run with pulsed RF?

STAT

Status bits in software (define the bits)

HSTA

Hardware status

SRF Interlocks - Per Cavity

W

INTLK_RESET_ALL

Reset all latched faults from RFS and Resonance/Interlock chassis

ACCL:L1B:0210:INTLK_RESET_ALL

R

QUENCH_FLT

Cavity quench fault, from RFS chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0210:QUENCH_FLT

R

QUENCH_LTCH

ACCL:L1B:0210:QUENCH_LTCH

W

QUENCH_BYP

ACCL:L1B:0210:QUENCH_BYP

R

QUENCH_BYP_RBV

ACCL:L1B:0210:QUENCH_BYP_RBV

R

STEPTEMP_FLT

Stepper temperature fault, from Interlock chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0210:STEPTEMP_FLT

R

STEPTEMP_LTCH

ACCL:L1B:0210:STEPTEMP_LTCH

W

STEPTEMP_BYP

ACCL:L1B:0210:STEPTEMP_BYP

R

STEPTEMP_BYP_RBV

ACCL:L1B:0210:STEPTEMP_BYP_RBV

R

CPLRTEMP1_FLT

Coupler temperature 1 fault, from Interlock chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0210:CPLRTEMP1_FLT

R

CPLRTEMP1_LTCH

ACCL:L1B:0210:CPLRTEMP1_LTCH

W

CPLRTEMP1_BYP

ACCL:L1B:0210:CPLRTEMP1_BYP

R

CPLRTEMP1_BYP_RBV

ACCL:L1B:0210:CPLRTEMP1_BYP_RBV

R

CPLRTEMP2_FLT

Coupler temperature 2 fault, from Interlock chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0210:CPLRTEMP2_FLT

R

CPLRTEMP2_LTCH

ACCL:L1B:0210:CPLRTEMP2_LTCH

W

CPLRTEMP2_BYP

ACCL:L1B:0210:CPLRTEMP2_BYP

R

CPLRTEMP2_BYP_RBV

ACCL:L1B:0210:CPLRTEMP2_BYP_RBV

R

PLL_FLT

FPGA PLL lock fault, from RFS chassis. Current status, latched status. Cannot be bypassed.

ACCL:L1B:0210:PLL_FLT

R

PLL_LTCH

ACCL:L1B:0210:PLL_LTCH

R

IOCWDOG_FLT

EPICS IOC watchdog fault, from RFS chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0210:IOCWDOG_FLT

R

IOCWDOG_LTCH

ACCL:L1B:0210:IOCWDOG_FLT

W

IOCWDOG_BYP

ACCL:L1B:0210:IOCWDOG_BYP

R

IOCWDOG_BYP_RBV

ACCL:L1B:0210:IOCWDOG_BYP_RBV

R

SSA_FLT

SSA permit fault, from RFS chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0210:SSA_FLT

R

SSA_LTCH

ACCL:L1B:0210:SSA_LTCH

W

SSA_BYP

ACCL:L1B:0210:SSA_BYP

R

SSA_BYP_RBV

ACCL:L1B:0210:SSA_BYP_RBV

SRF Interlocks - Per Rack (A or B)

R

CPLRVAC[A,B]_FLT

Coupler vacuum fault, from Interlock chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0200:CPLRVACA_FLT

R

CPLRVAC[A,B]_LTCH

ACCL:L1B:0200:CPLRVACA_LTCH

W

CPLRVAC[A,B]_BYP

ACCL:L1B:0200:CPLRVACA_BYP

R

CPLRVAC[A,B]_BYP_RBV

ACCL:L1B:0200:CPLRVACA_BYP_RBV

R

BMLNVAC[A,B]_FLT

Beamline vacuum fault, from Interlock chassis. Current status, latched status, bypass command, bypass status

ACCL:L1B:0200:BMLNVACA_FLT

R

BMLNVAC[A,B]_LTCH

ACCL:L1B:0200:BMLNVACA_LTCH

W

BMLNVAC[A,B]_BYP

ACCL:L1B:0200:BMLNVACA_BYP

R

BMLNVAC[A,B]_BYP_RBV

ACCL:L1B:0200:BMLNVACA_BYP_RBV

R

CRYOSUM[A,B]_FLT

Cryo summary fault, from local Cryo PLC. Current status, latched status, bypass command, bypass status

ACCL:L1B:0200:CRYOSUMA_FLT

R

CRYOSUM[A,B]_LTCH

ACCL:L1B:0200:CRYOSUMA_LTCH

W

CRYOSUM[A,B]_BYP

ACCL:L1B:0200:CRYOSUMA_BYP

R

CRYOSUM[A,B]_BYP_RBV

ACCL:L1B:0200:CRYOSUMA_BYP_RBV

SRF Interlocks - Per Cryomodule - Tentative

R

CRYOSUM_FLT

Cryo summary status from local Cryo PLC. Current status

ACCL:L1B:0200:CRYOSUM_FLT

R

HELEVEL_FLT

Cryo Helium level status from local Cryo PLC. Current status

ACCL:L1B:0200:HELEVEL_FLT

R

HEPRES_FLT

Cryo Helium pressure status from local Cryo PLC. Current status

ACCL:L1B:0200:HEPRES_FLT

R

CRYOHEARTBEAT_FLT

Cryo PLC heartbeat fault. Generated by RF software when cryo data stops updating or updates too slowly

ACCL:L1B:0200:CRYOPLC_HEARTBEAT

Cavity Ramp-Up and Calibration Output

R

QLOADED

Loaded Q

R

CAV_CONST

Cavity calibration constant (later will be merged with CAV:CAL_SCALE)

R

LDCOEF

Lorentz detuning

R

BCOEFM

State space B coefficient magnitude

R

BCOEFP

State space B coefficient phase

R

SSA:SLOPE

SSA slope

R

SSA:PED

SSA pedestal

R

SSA:MINX

SSA min X

Waveform Signals

Each SRF cavity has the following waveform signals:

Description	PV name, <SIG> in following section	Amplitude Units	Power Units	Phase
Drive (RFS chassis loopback)	DRV	sqrt(W)	W	degrees
Forward Power	FWD	sqrt(W)	W	degrees
Reverse/Reflected Power	REV	sqrt(W)	W	degrees
Cavity Probe	CAV	MV	mW	degrees
DAC (FPGA internal, input to DAC that drives SSA)	DAC	% of full DAC scale	(% of full DAC scale)^2	degrees
Detune (see below)	DF	Hz	N/A	N/A

For SRF systems, these PVs are provided for CAV, FWD, REV, DAC (and DRV only during expert diagnostics/troubleshooting.) Example PVs are for CAV.

R

<SIG>:AWF

Signal amplitude waveform

ACCL:L1B:0210:CAV:AWF

R

<SIG>:AMEAN

Mean of <SIG>:AWF

ACCL:L1B:0210:CAV:AMEAN

R

<SIG>:ASTD

Standard deviation of <SIG>:AWF

ACCL:L1B:0210:CAV:ASTD

R

<SIG>:ARSTD

Standard deviation of <SIG>:AWF divided by mean of <SIG>:AWF

ACCL:L1B:0210:CAV:ARSTD

R

<SIG>:AMIN

Minimum of <SIG>:AWF

ACCL:L1B:0210:CAV:AMIN

R

<SIG>:AMAX

Maximum of <SIG>:AWF

ACCL:L1B:0210:CAV:AWF

R

<SIG>:PWF

Signal phase waveform

ACCL:L1B:0210:CAV:PWF

R

<SIG>:PMEAN

Mean of <SIG>:PWF

ACCL:L1B:0210:CAV:PMEAN

R

<SIG>:PSTD

Standard deviation of <SIG>:PWF

ACCL:L1B:0210:CAV:PSTD

R

<SIG>:PRSTD

Standard deviation of <SIG>:PWF divided by mean of <SIG>:PWF

ACCL:L1B:0210:CAV:PRSTD

R

<SIG>:PMIN

Minimum of <SIG>:PWF

ACCL:L1B:0210:CAV:PMIN

R

<SIG>:PMAX

Maximum of <SIG>:PWF

ACCL:L1B:0210:CAV:PMAX

R

<SIG>:PWRWF

Signal power waveform

ACCL:L1B:0210:CAV:PWRWF

R

<SIG>:PWRMEAN

Mean of <SIG>:PWRWF

ACCL:L1B:0210:CAV:PWRMEAN

R

<SIG>:PWRSTD

Standard deviation of <SIG>:PWRWF

ACCL:L1B:0210:CAV:PWRSTD

R

<SIG>:PWRRSTD

Standard deviation of <SIG>:PWRWF divided by mean of <SIG>:PWRWF

ACCL:L1B:0210:CAV:PWRRSTD

R

<SIG>:PWRMIN

Minimum of <SIG>:PWRWF

ACCL:L1B:0210:CAV:PWRMIN

R

<SIG>:PWRMAX

Maximum of <SIG>:PWRWF

ACCL:L1B:0210:CAV:PWRMAX

R

<SIG>:IWF

Signal I waveform

ACCL:L1B:0210:CAV:IWF

R

<SIG>:QWF

Signal Q waveform

ACCL:L1B:0210:CAV:QWF

Other SRF Waveform Signals:

R

DF:WF

Detune frequency waveform. Calculated by software from cavity and forward signals. [Hz]

ACCL:L1B:0210:DF:WF

R

DF:MEAN

Mean of DF:WF

ACCL:L1B:0210:DF:MEAN

R

DF:STD

Standard deviation of DF:WF

ACCL:L1B:0210:DF:STD

R

DF:MIN

Minimum of DF:WF

ACCL:L1B:0210:DF:MIN

R

DF:MAX

Maximum of DF:WF

ACCL:L1B:0210:DF:MAX

R

BW:WF

Cavity bandwidth waveform. Calculated by software from cavity and forward signals. [Hz]

ACCL:L1B:0210:BW:WF

R

CTRL:IWF

P/I Controller Output I waveform. Calculated by software from cavity and DAC signals. [% of full scale, range -1 to 1]

ACCL:L1B:0210:CTRL:IWF

R

CTRL:QWF

P/I Controller Output Q waveform. Calculated by software from cavity and DAC signals. [% of full scale, range -1 to 1]

ACCL:L1B:0210:CTRL:QWF

Feedback

R

AMPFB_GAIN_P_RBV

Amplitude feedback proportional gain readback (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_P_RBV

R/W

AMPFB_GAIN_P

Amplitude feedback proportional gain setting (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_P

R

AMPFB_GAIN_I_RBV

Amplitude feedback integral gain readback (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_I_RBV

R/W

AMPFB_GAIN_I

Amplitude feedback integral gain setting (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_I

R

PHAFB_GAIN_P_RBV

Phase feedback proportional gain readback (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_P_RBV

R/W

PHAFB_GAIN_P

Phase feedback proportional gain setting (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_P

R

PHAFB_GAIN_I_RBV

Phase feedback integral gain readback (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_I_RBV

R/W

PHAFB_GAIN_I

Phase feedback integral gain setting (units not yet determined)

ACCL:L1B:0210:AMPFB_GAIN_I

Deployment and calibration attributes

By default, these should be write-protected during operation

Name		Description
		(from Chris Adolfsen. Garth wonders should this be a calibration attribute rather than physics interface?) Slow tuner start-up position prior to rf turn on - with the piezo voltages zeroed, the cavity would be tuned close to 1.3 GHz after the operating gradient is established - thus the initial detuning with rf off relative to 1.3 GHz is K*(operating gradient)^2
		(from Chris Adolfsen. Garth wonders should this be a calibration attribute rather than physics interface?) Slow tuner park position - this is the position the tuner would be set if one wants to detune the cavity so it does not interact with the beam.
Q0		Q₀ measurement from partner labs, delivered with the cryomodule
Qext		Qext measured in-situ (last measurement – used to calibrate cavity probe signal based on discharge power)
LFD		Lorentz Force Detuning K factor(Hz/(MV/m)^2) measured in-situ
		Calibration of the slow tuner (Hz/step) measured in-situ
		Calibration of the piezo tuners (Hz/volt) measured in-situ
Signal calibration. The PVs below will be provided for FWD, REV, DRV signals.
Measured values
<SIG>:CAL_ADC_10DBM	R/W	ADC counts at 10 dBm. EPICS software uses this to calculate RF power at full scale.
<SIG>:CAL_LOSS_CABLE	R/W	Measured cable losses used in signal calibration. Positive value in dB.
<SIG>:CAL_LOSS_CPLR	R/W	Measured coupler loss used in signal calibration. Positive value in dB.
<SIG>:CAL_LOSS_ATTEN	R/W	Fixed attenuator used in signal calibration. Positive value in dB.
<SIG>:CAL_LOSS_OTHER	R/W	Unattributed measured loss used in signal calibration. Positive value in dB.
EPICS-calculated values
<SIG>:CAL_REF_PWR	R	RF power at ADC full scale. In dBm. Analogous PVs exist for reverse and drive (aka loopback) signals.
<SIG>:CAL_LOSS_TOTAL	R	Total (of cable, coupler, atten, other) loss used in signal calibration. Positive value in dB.
<SIG>:SCALE	R	Calibration scale factor to convert raw ADC counts to amplitude in sqrt(Watts). Calculated internally by RF software, based on system losses and ADC power at full scale.
Signal calibration for Cavity Probe (CAV)
CAV:CAL_SCALE	R/W	Calibration scale factor to convert cavity probe raw ADC counts to amplitude in MV. Calculated by LLRF calibration sequence. See CAV:SCALE for more info.
CAV:SCALE	R	Calibration scale factor to convert cavity probe raw ADC counts to amplitude in MV. Is equal to product of CAV:CAL_SCALE and beam-based FUDG scale factor.


		Chassis and ADC scale factor, or polynomial coefficients. From lab measurements of chassis to convert ADC units to physics units
		PI(no D) loop parameters for amplitude and phase loops. Maybe PKp, PKi, GKp, GKi
		Open loop amplitude and phase DAC settings
		Control loop status (open, closed)

Other attributes for operations - In Progress/Tentative

Name	Description
V	Chassis power supply voltage
T	Chassis board temperature
DC	SSA enable/disable internal DC power
	SSA RF enable, how to distinguish from global RF enable?
PzVout	Output voltage to the piezo tuning motor
PzHz	Expected tuning change from PzVout

Expert attributes, not for use on operations screens

Name	Description
	Firmware MD5
	BMB7 board serial #
	Digitizer board serial #
	Chassis serial # and/or Depot number

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