From HFML-FELIX Wiki
The power meter daemon
[edit | edit source]| MQTT daemon | |
 | |
| measure FELIX power | |
| Language | Python |
|---|---|
| Hosts | pi8 |
| Repository | unspecified |
Introduction
[edit | edit source]The power meter daemon measures each shot of FELIX it detects and reports the value via MQTT. The powermeter also communicates with the attenuators via MQTT. The daemon will try to protect the powermeter device by inserting 3 dB attenuation while it is measuring (unless the gun is running at 25 MHz). It will not insert the flipper mirror until a mimimum of 3 dB attenuation is inserted. Before extracting the flipper mirror, the daemon will insert all attenuation to protect the users' experiments.
The powermeter can use the integral of the pyro to estimate the power of each shot, if it has noted the ratio between the actual power and the pyro integral before at that wavelength. For that reason, it is advisable to use the power scan feature to record the powermeter/pyro integral ratio over the whole range of interest.
MQTT
[edit | edit source]dependencies
[edit | edit source]The Powermeter daemon depends on these topics for the correct interpretation of the state of the various devices to control.
| Topic | Description | Reason |
|---|---|---|
| FELIX/ETH484/ETH484-11/digital/5/state | fel mirror out | fel selection |
| FELIX/ETH484/ETH484-11/digital/6/state | fel mirror in | fel selection |
| FELIX/ETH484/ETH484-11/digital/7/state | flipper mirror state in | state machine |
| FELIX/ETH484/ETH484-11/digital/8/state | flipper mirror state out | state machine |
| FELIX/ETH484/ETH484-11/relay/4/state | flipper mirror relay | state machine |
| FELIX/ETH484/ETH484-11/digital/1/state | lw 5 dB in | attenuation |
| FELIX/ETH484/ETH484-11/digital/3/state | lw 3 dB in | attenuation |
| FELIX/ETH484/ETH484-04/digital/+/state | sw 10,10,10,5 dB in | attenuation |
| FELIX/ETH484/ETH484-05/digital/+/state | sw 3 dB in, lw 10,10,10 dB in | attenuation |
| FELIX/userstation/current | current userstation | optional, convenience |
| FELIX/spectrum_analyzer/mean_wavelength | spectrum analyzer power | offline power indication |
| FELIX/spectrum_analyzer/spectrum_integral | for offline power indication | offline power indication |
commands
[edit | edit source]| Topic | Description | Values |
|---|---|---|
| FELIX/powermeter/measure_request/command | whether the powermeter will actively try to set up for measuring | boolean, True means active, False means passive |
| FELIX/powermeter/protection/command | protection of the powermeter by minimum of 3 dB attenuation | boolean, True means active, False means inactive |
| FELIX/powermeter/strict/command | whether the protection must be 3 dB exactly | boolean, True means strictly 3 dB, False means 3 dB or more is ok |
| FELIX/powermeter/refresh | resend all statusses | value does not matter |
| FELIX/powermeter/log_level | set log level | string (notset/debug/info/warning/error/critical) or integer (e.g. 20) |
| FELIX/powermeter/clients/stop | this topic is for remote shutdown of clients (the daemon itself takes no action) | False to stop clients, True to terminate clients |
statusses
[edit | edit source]| Topic | Description | Values |
|---|---|---|
| FELIX/powermeter/state | state machine state | text |
| FELIX/powermeter/shot/json | packed dictionary of the parameters of this shot (see items below) | json string |
| FELIX/powermeter/shot/timestamp | timestamp of this shot | double (unix timestamp) |
| FELIX/powermeter/shot/raw_power | power as measured by Thorlabs powermeter | float (mJ) |
| FELIX/powermeter/shot/real_power | power corrected for attenuation | float (mJ) |
| FELIX/powermeter/shot/estimated_power | power estimated from pyro signal | float (mJ) |
| FELIX/powermeter/shot/attenuation | the attenuation used in calculating this shot's real power | float (dB) |
| FELIX/powermeter/sensor | the string identifier provided by the attached sensor | text |
| FELIX/powermeter/attenuation | the current attenuation | float (dB) |
| FELIX/powermeter/flipper_mirror | the position of the flipper mirror | boolean, True means in, False means out |
| FELIX/powermeter/measure_request/state | whether the powermeter will actively try to set up for measuring | boolean, True means active, False means passive |
| FELIX/powermeter/protection/state | protection of the powermeter by minimum of 3 dB attenuation | boolean, True means active, False means inactive |
| FELIX/powermeter/strict/state | whether the protection must be 3 dB exactly | boolean, True means strictly 3 dB, False means 3 dB or more is ok |
| FELIX/powermeter/fel/current | which beamline is active, hence which attenuator set will be operated | integer, 1 for FEL1/lw, 2 for FEL2/sw |
| FELIX/powermeter/servers/host_pid | server declaration | json formatted text {"startdate": "date time", "state": "active or passive", "hostname": "hostname", "pid": pid} |
| FELIX/powermeter/clients/host_pid | client declaration Note: published by clients, not by this daemon |
json formatted text {"hostname": "hostname", "pid": pid,"state":"master or slave","subsystem":"powermeter","starttime":timestamp} |
| FELIX/powermeter/daemon_time | system time of the host the daemon runs on | unix timestamp (e.g. 1550680653.91) |
| FELIX/powermeter/daemon_time/readable | system time of the host the daemon runs on | human-readable timestamp (e.g. Wed Feb 20 17:37:59 2019) |
Programmer's details
[edit | edit source]State machine logic
[edit | edit source]- beamlinewait
- fel selection != None -> 1
- idle
- measure request == TRUE -> 3
- insert protection
- measure request == FALSE -> 2
- >= 3dB inserted -> 4
- insert flipper mirror
- flipper mirror == IN -> 5
- measure request == FALSE -> 6
- measuring
- <3dB inserted? -> insert 3 dB
- flipper mirror == OUT -> 4
- measure request == FALSE -> 6
- insert all attenuation
- all attenuation inserted? -> 2
