Changes for page Trigger Howto

Last modified by sndueste on 2023/07/07 11:28
From version 12.1
edited by sndueste
on 2019/09/17 15:03
Change comment: There is no comment for this version
To version 7.1
edited by sndueste
on 2019/09/17 13:44
Change comment: There is no comment for this version

Summary

Details

Page properties
Content
... ... @@ -2,8 +2,7 @@
2 2  
3 3  {{toc/}}
4 4  
5 -= Introduction (user panel)
6 - =
5 += Introduction =
7 7  
8 8  The MTCA based triggers have a jitter in the few ps range, the delay can be shifted in 1 ns steps (over many ms), one can choose between 10 Hz triggers, frequencies locked to the pulses (e.g. 1MHz) and the actual bunch patterns. A detailed description can be found in [[x2Timer manual>>attach:x2Timer.pdf]].
9 9  
... ... @@ -14,7 +14,7 @@
14 14  
15 15  \\
16 16  
17 -= Different trigger events (starting points) =
16 += different trigger events (starting points) =
18 18  
19 19  one can configure each channel for an individual trigger event
20 20  
... ... @@ -104,21 +104,17 @@
104 104  
105 105  \\
106 106  
107 -= Set a constant frequency to a channel =
108 -
109 -=
106 += Set a constant frequency to a channel
110 110  [[image:attach:image2019-9-17_13-18-9.png||height="250"]][[image:attach:image2019-9-17_13-18-37.png||height="149"]] =
111 111  
112 112  \\
113 113  
111 +\\
112 +
114 114  The timer card provides the option to generate  frequencies that are synched to the FEL reprate on the ps level. One can set 3 Clocks by deviding the reference frequency of 54.2 MHz by n.** Please check (using the Expert overview ) before changing a frequency of it is used for some other channel !!**
115 115  
116 116  Since our main FEL frequency is 100.31 MHz the dividers are not straight forward:
117 117  
118 -[[image:attach:image2019-9-17_14-22-29.png||width="450" align="right"]]
119 -
120 -\\
121 -
122 122  (% class="wrapped" %)
123 123  |=(((
124 124  Clock frequency
... ... @@ -151,14 +151,6 @@
151 151  539
152 152  )))
153 153  
154 -\\
155 -
156 -\\
157 -
158 -\\
159 -
160 -\\
161 -
162 162  Once a clock is configured with the right frequency one can choose in the "expert panel" of the according channel the "FPGA clock" in the "input source select"  chooser.
163 163  
164 164  \\
... ... @@ -165,73 +165,12 @@
165 165  
166 166  \\
167 167  
168 -\\
155 +* in order to generate a stable frequency one has to set the input source to FPGA clock (and use dividers to get the desired frequency)
156 +* to generate the burst patterns of the FEL one has to choose a trigger event (best 116 for FLASH 2 and 16 for FLASH1) and activate Destination 1 for FLASH1 and Destination 2 for FLASH2 . finally one has to assign the activated Bunch pattern mask to the trigger channel of choice . now the pattern can be shifted and the trigger width can be changed as with the 10 Hz triggers. **IMPORTANT: to move the bunchtrain to the desired starting point the DELAY in the expert panel (see below) has to be used. The Trigger in the user panel (see above) has to be set to 0 !!!**
157 +[[~[~[image:url:http://hasfweb.desy.de/pub/Setup/TriggerHowto/mtcatrigger2k.png~|~|alt="mtcatrigger2k.png" width="607" height="458"~]~]>>attach:mtcatrigger2k.png]]
169 169  
170 -One has to set the delay to values less than the repetition rate ... (so for 1 MHz between 0 and 990 µs)  and the trigger width also less than the rep rate ...
159 +here an example defining the bunch pattern for FLASH1 to mask 1
171 171  
172 172  \\
173 173  
174 -\\
175 -
176 -\\
177 -
178 -This results in a continuous train of pulses with the set trigger width :
179 -
180 -= Creating an (own) burst trigger =
181 -
182 -One can use now a SECOND trigger channel which is set to a regular 10 Hz trigger  and gate the clock output to create a burst with defined start point and length,
183 -
184 -For the example we use the FRONT.TRG2 (BL3 Trg5) as gate pulse which defines the length of the burst (set with the trigger width) and the (rough) starting point of the burst. This trigger is only used as gate and the physical trigger output is NOT used.
185 -
186 -The  second channel (here FRONT.TRG3 (BL3 Trg6) which is set to the clock frequency defines the reprate (by the FPGA clock setting) , the exact starting point of the first trigger ( by the delay ) and the width of the  MHz/kHz triggers (width).
187 -
188 -**To get from the clock to the burst trigger** one has to:
189 -
190 -* set the  "2nd source select" to the gate trigger ( here FRONT.TRG2) - this defines a second source to considder for the trigger output.
191 -* and the "output source select" to "AND 2nd Ch."  this finally only sends a trigger if on both inputs (clock and gate) we have a high signal.
192 -
193 -\\
194 -
195 -[[image:attach:image2019-9-17_14-35-5.png||height="250"]] [[image:attach:image2019-9-17_14-34-38.png||width="400"]]
196 -
197 -\\
198 -
199 -\\
200 -
201 -= Real bunch trigger  - get a trigger for each FEL pulse =
202 -
203 -\\
204 -
205 -Sometimes it is convenient to get a trigger pulse for each pulse in the FEL. thus if the FEL number of bunches or reprate are changed, the trigger adapts accordingly.
206 -
207 -For this one has to select the source of interest in the expert overview panel (tab: "Bunch pattern") ... well for us this is FLASH1 (FL1D) or FLASH2 (FL2D)
208 -
209 -There are 6 different bunch pattern "channels" one can configure. Typically only 2 are needed ... And in each one there are 6 selectors to choose sources . We only need one - it does not matter in which one is used.
210 -
211 -[[~[~[image:attach:image2019-9-17_14-51-28.png~|~|height="250"~]~]>>attach:image2019-9-17_14-51-28.png]][[image:attach:image2019-9-17_14-47-15.png||thumbnail="true" height="199"]]
212 -
213 -\\
214 -
215 -In the expert panel one can now choose the configured "Bunch Pattern" as "Input source select"
216 -
217 -**NOTE: To shift the burst in time one can no longer use the delay of the individual channel BUT the delay in the "Bunch pattern" tab in the expert overview! This now shifts all bursts ... so you better know what you are doing. typically the burst is already shifted to the actual FEL timing ... Shifting the timing should be discussed with the beamline scientist / local contact ...**
218 -
219 -\\
220 -
221 -[[image:attach:image2019-9-17_14-52-27.png||height="248"]][[image:attach:image2019-9-17_14-52-40.png||height="250"]]
222 -
223 -\\
224 -
225 -\\
226 -
227 -\\
228 -
229 -\\
230 -
231 -\\
232 -
233 -\\
234 -
235 -\\
236 -
237 -\\
163 +[[here is a link to the old VME trigger system>>doc:FLASH.VMETrigger]]