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It's a common question to ask what are the rates that the accelerator can generate.  The table below lists the rates that are natural for the accelerator.  These are the periodic rates that repeat exactly at the ~0.98 second period of the timing/MPS system.  Of course, we can generate other rates as well that aren't exactly periodic by doing the sort of thing you described - dropping shots or irregular sequences.  This has been useful for the OPCPA laser development in deciding the exact frequencies they will support.

If a base accelerator rate is chosen (e.g. 33kHz) then other rates having the same prime factors as the accelerator rate are allowed, according to this table:

(python3_env) [weaver@lcls-dev3 lcls2-timing-patterns]$ python lcls/fixed_rate_table.py

Matt provides this example of how you can determine if various trigger rates overlap: 16kHz (16581 in the table) has factors (2,2,2,7).  102Hz has factors (2,2,5,5,7,13).  It's missing one factor of 2, so it only overlaps 1/2 of the time.  51Hz has (2,2,2,5,5,7,13), so it contains all the factors from 16kHz and thus overlaps 100%.

If a base accelerator rate is chosen (e.g. 33kHz) then other rates having the same prime factors as the accelerator rate are allowed, according to this table:

(python3_env) [weaver@lcls-dev3 lcls2-timing-patterns]$ python lcls/fixed_rate_table.py

 rate, Hz  | factor | factors
 rate, Hz  | factor | factors
 928571          1   1
 464285          2   (2,)
 232142          4   (2, 2)
 185714          5   (5,)
 132653          7   (7,)
 116071          8   (2, 2, 2)
  92857         10   (2, 5)
  71428         13   (13,)
  66326         14   (2, 7)
  58035         16   (2, 2, 2, 2)
  46428         20   (2, 2, 5)
  37142         25   (5, 5)
  35714         26   (2, 13)
  33163         28   (2, 2, 7)
  26530         35   (5, 7)
  23214         40   (2, 2, 2, 5)
  18571         50   (2, 5, 5)
  17857         52   (2, 2, 13)
  16581         56   (2, 2, 2, 7)
  14285         65   (5, 13)
  13265         70   (2, 5, 7)
  11607         80   (2, 2, 2, 2, 5)
  10204         91   (7, 13)
   9285        100   (2, 2, 5, 5)
   8928        104   (2, 2, 2, 13)
   8290        112   (2, 2, 2, 2, 7)
   7428        125   (5, 5, 5)
   7142        130   (2, 5, 13)
   6632        140   (2, 2, 5, 7)
   5306        175   (5, 5, 7)
   5102        182   (2, 7, 13)
   4642        200   (2, 2, 2, 5, 5)
   4464        208   (2, 2, 2, 2, 13)
   3714        250   (2, 5, 5, 5)
   3571        260   (2, 2, 5, 13)
   3316        280   (2, 2, 2, 5, 7)
   2857        325   (5, 5, 13)
   2653        350   (2, 5, 5, 7)
   2551        364   (2, 2, 7, 13)
   2321        400   (2, 2, 2, 2, 5, 5)
   2040        455   (5, 7, 13)
   1857        500   (2, 2, 5, 5, 5)
   1785        520   (2, 2, 2, 5, 13)
   1658        560   (2, 2, 2, 2, 5, 7)
   1485        625   (5, 5, 5, 5)
   1428        650   (2, 5, 5, 13)
   1326        700   (2, 2, 5, 5, 7)
   1275        728   (2, 2, 2, 7, 13)
   1061        875   (5, 5, 5, 7)
   1020        910   (2, 5, 7, 13)
    928       1000   (2, 2, 2, 5, 5, 5)
    892       1040   (2, 2, 2, 2, 5, 13)
    742       1250   (2, 5, 5, 5, 5)
    714       1300   (2, 2, 5, 5, 13)
    663       1400   (2, 2, 2, 5, 5, 7)
    637       1456   (2, 2, 2, 2, 7, 13)
    571       1625   (5, 5, 5, 13)
    530       1750   (2, 5, 5, 5, 7)
    510       1820   (2, 2, 5, 7, 13)
    464       2000   (2, 2, 2, 2, 5, 5, 5)
    408       2275   (5, 5, 7, 13)
    371       2500   (2, 2, 5, 5, 5, 5)
    357       2600   (2, 2, 2, 5, 5, 13)
    331       2800   (2, 2, 2, 2, 5, 5, 7)
    285       3250   (2, 5, 5, 5, 13)
    265       3500   (2, 2, 5, 5, 5, 7)
    255       3640   (2, 2, 2, 5, 7, 13)
    212       4375   (5, 5, 5, 5, 7)
    204       4550   (2, 5, 5, 7, 13)
    185       5000   (2, 2, 2, 5, 5, 5, 5)
    178       5200   (2, 2, 2, 2, 5, 5, 13)
    142       6500   (2, 2, 5, 5, 5, 13)
    132       7000   (2, 2, 2, 5, 5, 5, 7)
    127       7280   (2, 2, 2, 2, 5, 7, 13)
    114       8125   (5, 5, 5, 5, 13)
    106       8750   (2, 5, 5, 5, 5, 7)
    102       9100   (2, 2, 5, 5, 7, 13)
     92      10000   (2, 2, 2, 2, 5, 5, 5, 5)
     81      11375   (5, 5, 5, 7, 13)
     71      13000   (2, 2, 2, 5, 5, 5, 13)
     66      14000   (2, 2, 2, 2, 5, 5, 5, 7)
     57      16250   (2, 5, 5, 5, 5, 13)
     53      17500   (2, 2, 5, 5, 5, 5, 7)
     51      18200   (2, 2, 2, 5, 5, 7, 13)
     40      22750   (2, 5, 5, 5, 7, 13)
     35      26000   (2, 2, 2, 2, 5, 5, 5, 13)
     28      32500   (2, 2, 5, 5, 5, 5, 13)
     26      35000   (2, 2, 2, 5, 5, 5, 5, 7)
     25      36400   (2, 2, 2, 2, 5, 5, 7, 13)
     20      45500   (2, 2, 5, 5, 5, 7, 13)
     16      56875   (5, 5, 5, 5, 7, 13)
     14      65000   (2, 2, 2, 5, 5, 5, 5, 13)
     13      70000   (2, 2, 2, 2, 5, 5, 5, 5, 7)
     10      91000   (2, 2, 2, 5, 5, 5, 7, 13)
      8     113750   (2, 5, 5, 5, 5, 7, 13)
      7     130000   (2, 2, 2, 2, 5, 5, 5, 5, 13)
      5     182000   (2, 2, 2, 2, 5, 5, 5, 7, 13)
      4     227500   (2, 2, 5, 5, 5, 5, 7, 13)
      2     455000   (2, 2, 2, 5, 5, 5, 5, 7, 13)
      1     910000   (2, 2, 2, 2, 5, 5, 5, 5, 7, 13)

...

Another important method (used especially for low rate 1,10,100Hz triggers that are in-synch with the beam) is to use an event-code generated by ACR (see Control Sequence Bit for currently supported event codes). These event codes already include a destination setting.

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Some details:

 cpo thinks event codes like "SC_SXR BSA" (e.g. 100Hz is eventcode 30) on that page would be commonly used by the hutches. NOTE: We have seen empirically that these event codes do not include a destination setting, so it is necessary to also select destination 4 with the "select" field set to "inclusive" with them.  Matt writes: "Event code 30 will follow the offset used by SXR, but it isn't aware of MPS mitigating the beam rate.  We use the destination 4 filter to also pickup when MPS has inhibited the beam."

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Some details:

• there are 288 bits of "event there are 288 bits of "event codes" available
  • some have well-defined meanings, like the low-rate ones described above (in progress)
  • 16 highest bits are hutch specific for sequences (272-287)
  • DAQ readout groups are "extra bits" included at end of timing frame
• timing frames have "destinations": e.g. bykiks, and bykikh both go to "bsy" dump
• unlike LCLS1 we will not be using event-codes to understand when bykiks has fired: use destinations instead, in particular DumpBSY for "dropped" or "background" shots
• some devices reference to "sequencer engineer number" and "sequence bit number" instead of "eventcode".  The formula to convert between the two: eventcode=(sequenceEngine#<<16 | sequencerBit#).

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In this example the XPM is configured to insert event codes 272-287 into the timing stream.  Four event codes are generated by each sequence engine within the XPM.  The XPM has 4 sequence engines allowing 16 event codes total.

A current example for A current example for doing this is done by executing:

(first use Matt's high-level utility to generate two event codes that run at 10Hz and 100Hz (periods 91000 and 9100 respectively)

(ps-4.5.26) drp-srcf-mon001:psana$ periodicgenerator -p 91000 9100 -s 0 0 -d '10Hz' '100Hz' >& 10hz_100hz.py

(now program sequence engine 0 and start it using the python code generated above. since we're programming engine 0, the first two event codes will be 272,273 according to the above table)

(this command must be executed on a node that can access the XPM PV's, e.g. drp-srcf-*)

(ps-4.5.26) drp-srcf-mon001:psana$ seqprogram --seq 04:10hz_100hz.py --pv DAQ:NEH:XPM:3 --start
** engine 0 fname 10hz_100hz.py **
descset  None
seqcodes {0: '10Hz', 1: '100Hz'}
Remove -1
idx 2
Removing seq 2
[10, 1, 5, 3, 0, 0, 0, 0, 2, 0, 6, 2048, 0, 0, 0, 3, 2, 1, 3, 3, 0, 0, 2, 0, 6, 908, 0, 0, 0, 1, 5, 2, 0, 0, 0, 0, 3, 2, 1, 0, 8, 0, 0, 2, 0, 6, 2048, 0, 0, 0, 3, 2, 6, 3, 3, 0, 0, 2, 0, 6, 908, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0]
Confirmed ninstr 10
Sequence  found at index 2
desc ['10Hz', '100Hz', '', '', '', '', '', '', '', '', '', '', 'burst', '', '', '']
seqcodes_pv epics:nt/NTTable:1.0 
    string[] labels [EventCode, Description, Rate, Enabled]
    structure value
        int[] EventCode [272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287]
        string[] Description [10Hz, 100Hz, , , , , , , , , , , burst, , , ]
        int[] Rate [11,102,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
        byte[] Enabled [1,1,1,1,0,0,0,0,0,0,0,0,1,1,1,1]
    string descriptor 
    alarm_t alarm
        int severity 0
        int status 0
        string message 
    time_t timeStamp
        long secondsPastEpoch 1683163040
        int nanoseconds 339389440
        int userTag 0

(now query the xpm to see what is running in the 4 sequence engines, each having 4 event codes)

(ps-4.5.26) drp-srcf-mon001:psana$ pvget DAQ:NEH:XPM:3:SEQCODES
DAQ:NEH:XPM:3:SEQCODES 2023-05-03 18:17:31.339    
EventCode Description Rate Enabled
      272        10Hz   10       1
      273       100Hz  102       1
      274                0       1
      275                0       1
      276                0       0
      277                0       0
      278                0       0
      279                0       0
      280                0       0
      281                0       0
      282                0       0
      283                0       0
      284       burst    0       1
      285                0       1
      286                0       1
      287                0       1
(ps-4.5.26) drp-srcf-mon001:psana$ 

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self.pv_xpm_part_base = pv_base + ':XPM:%d:PART:%d' % (xpm_master, platform)
self.pva.pv_put(self.pva.pvStepEnd, self.readoutCumulative)

Generating a Low Rate Sequence

From Matt.

periodicgenerator --period 1820000 --start_bucket 91000 --description 'Example 0.5Hz sequence' > 0.5Hseq.py
(ps-4.6.1) bash-4.2$ seqplot --seq 0:0.5Hseq.py --time 4.0
eng 0 fn 0.5Hseq.py
0: FixedRateSync(929kHz) # occ(2048)
1: Branch to line 0 until ctr3=43
2: FixedRateSync(929kHz) # occ(888)
3: ControlRequest word 0x1 [0]
4: FixedRateSync(929kHz) # occ(2048)
5: Branch to line 4 until ctr3=843
6: FixedRateSync(929kHz) # occ(488)
7: Branch unconditional to line 0
start, stop: 0,3640000
engine exited request 0  instr 1  returnaddr None  frame 3642047  ccnt [0, 0, 0, 0]

Should show eventcode 272 at bucket 91,000 and every 1,820,000 (2 seconds) after that.

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