This section describes what an AIDA-PVA user should know about accessing the SLC Buffered Data through AIDA-PVA. This data service gives access to the so called "Buffered BPM Data" acquisition facilities of the SLC Control System, in the SLAC accelerator complex. For general information on xusing AIDA-PVA see Basic Users Guide to Aida, and the EPICS javadoc.

Summary

Acquires SLC control system pulse synchronized "Buffered Data" and status information for the given set of devices and pulses.

Synopsis

	PV	Arguments	Description
1.4.1	`<display-group-mnemonic>:BUFFACQ`	`BPMD` `BPMS` [ `NRPOS` ]	Buffered Acquisition
	`<display-group-mnemonic>:BUFFACQ`	`BPMD` `DEVS` [ `NRPOS` ]

1.4.1. Buffered Acquisition

<display-group-mnemonic>:BUFFACQ
- BPMD* : measurement-definition-number
- BPMS* : list-of-device-names
- NRPOS : number-of-pulses
<display-group-mnemonic>:BUFFACQ
- BPMD* : measurement-definition-number
- DEVS* : list-of-device-names
- NRPOS : number-of-pulses

Buffered BPM data, is the name given to the pulse-by-pulse data acquisition system.

Makes a buffered acquisition reading of each given device, in the measurement definition group specified in the INSTANCE part of the query, under the BPM Measurement Definition specified by the BPMD argument, at each beam crossing for the number of pulses given by NRPOS.

The service returns a table of results - the x and y position values and the tmit, given in one row per device, per pulse.

The following device types are supported:

BPM
- x (mm)
- y (mm)
- tmit (num particles estimated)
TORO
- tmit
KLYS and SBST
- phase
GAPM data

Note: A table is returned. Since the kind of data one gets back from these device types may differ, some elements of the table of data you get back should be ignored.

Arguments

Argument Names	Argument Values	Description
`BPMD`*	`<measurement-definition-number>`	integer This specifies the timing profile of the acquisition. Each `BPMD` corresponds to exactly one DGRP. To find likely BPMDs, go to the BPM Device panel of a SCP and hit the 'HELP' button, then select the button corresponding to the bpm orbit you would have wanted to see. The button name for that acquisition, as displayed in the help, is the BPMD for the selected orbit. Use that number for this parameter. Eg `BPMD=57` is the primary BPMD for the DGRP `NDRFACET`, and so will be the main one used for FACET.
`BPMS`*	`<list-of-device-names>`	The names of the devices from which a user would like the Buffered service to acquire data. Device names for the following devices: `BPM`, `TORO`, `GAPM`, `KLYS` or `SBST`. Either `BPMS` or `DEVS` must be specified but not both
`DEVS`*	`<list-of-device-names>`	The names of the devices from which a user would like the Buffered service to acquire data. Device names for the following devices: `BPM`, `TORO`, `GAPM`, `KLYS` or `SBST`. Either `BPMS` or `DEVS` must be specified but not both
`NRPOS`	`<number-of-pulses>`	positive integer `1 =< N >= 10000`: Default is `1`. In theory, this parameter can range up to `2800`, but some things must be borne in mind. Firstly, roughly speaking the minimum time it could take a buffered acquisition to complete, is `NRPOS`/machine-rate-in-Hz. But, the SCP in fact adds time to this theoretical minimum heuristically, to give the micros time to prep the acquisition. Secondly, AIDA-PVA's network's default timeout is small so you will need to increase it if you expect the acquisition will take more than a few seconds. So, in practice, limit your NRPOS to numbers that will result in relatively short acquisitions, or increase the timeout.

Return value

TYPE	Return Column	Column Type	Description
`TABLE`	`name`	`STRING_ARRAY`	name of each BPM
	`pulseId`	`INTEGER_ARRAY`	pulse ID
	`x`	`FLOAT_ARRAY`	x offsets (mm)
	`y`	`FLOAT_ARRAY`	y offsets (mm)
	`tmits`	`FLOAT_ARRAY`	tmits (num particles)
	`stat`	`INTEGER_ARRAY`	(32 bit field)
	`goodmeas`	`BOOLEAN_ARRAY`	true = good, false = bad

Note: Return value for BPM device shown below. TORO, GAPM, KLYS or SBST will be different.

Examples

Operations

NDRFACET:BUFFACQ BPMD=57 BPMS=["BPMS:LI11:501"]
NDRFACET:BUFFACQ BPMD=57 NRPOS=180 BPMS=["BPMS:LI11:501", "BPMS:LI11:601", "BPMS:LI11:701", "BPMS:LI11:801"]

Response

BPM Name	pulse ID	y offset	x offset	num particles	stat	goodmeas
		mm	mm	coulomb
`name`	`pulseId`	`x`	`y`	`tmits`	`stat`	`goodmeas`
`BPMS:PR10:8022`	71312	`0.066477716`	`-0.066477716`	`1.0E-10`	`1`	`15`
`BPMS:PR10:8032`	71313	`1.0967255`	`-1.0967255`	`1.0E-10`	`1`	`15`
`BPMS:PR10:8042`	71314	`0.058775872`	`-0.058775872`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9012`	71315	`-0.9340391`	`0.9340391`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9022`	71316	`0.051719327`	`-0.051719327`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9032`	71317	`1.00613`	`-1.00613`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9042`	71318	`0.09205267`	`-0.09205267`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9052`	71319	`-0.9331402`	`0.9331402`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9062`	71320	`0.08750657`	`-0.08750657`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9072`	71321	`1.0201329`	`-1.0201329`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9082`	71322	`0.031224214`	`-0.031224214`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9092`	71323	`-0.9497527`	`0.9497527`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9102`	71324	`0.004137807`	`-0.004137807`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9112`	71325	`1.0184262`	`-1.0184262`	`1.0E-10`	`1`	`15`
`BPMS:PR10:9122`	71326	`0.09096262`	`-0.09096262`	`1.0E-10`	`1`	`15`
...	...	...	...	...	...	...
`BPMS:PR10:6142`	71328	`1.0156763`	`-1.0156763`	`1.0E-10`	`1`	`15`
`BPMS:PR10:6152`	71329	`0.028162582`	`-0.028162582`	`1.0E-10`	`1`	`15`
`BPMS:PR10:6162`	71330	`-0.9782702`	`0.9782702`	`1.0E-10`	`1`	`15`
`BPMS:PR10:7012`	71331	`0.015536556`	`-0.015536556`	`1.0E-10`	`1`	`15`
`BPMS:PR10:7022`	71332	`1.0258453`	`-1.0258453`	`1.0E-10`	`1`	`15`
`BPMS:PR10:7032`	71333	`0.04465735`	`-0.04465735`	`1.0E-10`	`1`	`15`
`BPMS:PR10:7042`	71334	`-0.9776291`	`0.9776291`	`1.0E-10`	`1`	`15`
`BPMS:PR10:8012`	71335	`1.5865061E`-4	`-1.5865061`	`1.0E-10`	`1`	`15`

Increasing timeout for AIDA-PVA requests

For requests that can take a long time you may need to increase the request timeout. Depending on how you are accessing AIDA-PVA the method you use to do this will vary.

method	Steps
matlab	1. Add the `timeout()` to the builder e.g. `.timeout(30)`
aida-pva-client	1. Add the `timeout()` to the builder e.g. `.timeout(30)`
pvaClient	1. Add the `timeout` field to query e.g. `.addQueryInt("timeout")` 2. Set `timeout` field to desired value e.g. `uri.getQuery().getIntField("timeout").put(30)` 3. Set pvaClient timeout e.g. `client.channel(pvName, "pva", 30.0)`
PvAccess	1. Add the `timeout` field to query e.g. `.addQueryInt("timeout")` 2. Set `timeout` field to desired value e.g. `uri.getQuery().getIntField("timeout").put(30)` 3. Set pvAccess timeout when executing e.g. `client.request(uri.getPVStructure(), 30.0)`
`pvcall`	1. Add the `timeout` field to query e.g. `... TIMEOUT=30` 2. Set `pvcall` timeout when executing e.g. `pvcall -w 30 ...`
`eget`	1. Add the `timeout` field to query e.g. `... TIMEOUT=30` 2. Set `eget` timeout when executing e.g. `eget -w 30 ...`

CLI and Code Examples

Commandline Examples

example type

example

pvcall

pvcall -w 30 "NDRFACET:BUFFACQ" TIMEOUT=30 BPMD=57 NRPOS=10 BPMS='["BPMS:LI02:501", "BPMS:DR12:334"]'

eget

eget -w 30 -s NDRFACET:BUFFACQ -a TIMEOUT 30 -a BPMD 57 -a NRPOS 10 -a BPMS '["BPMS:LI02:501", "BPMS:DR12:334"]'

Matlab Examples

Note: For general details about accessing AIDA-PVA from matlab see User Guide for Matlab Users

action

example

Get

try
    builder = pvaRequest('NDRFACET:BUFFACQ');
    builder.with('BPMD', 57);
    builder.with('NRPOS', 10);
    builder.with('BPMS', { 'BPMS:LI11:501' 'BPMS:DR12:334'});
    builder.timeout(30);
    mstruct = ML(builder.get())
    mstruct.values.x(1:10)
catch e
    handleExceptions(e);
end
mstruct =
            size: 20
          labels: {'BPM Name'  'pulse id'  'x offset (mm)'  'y offset (mm)'  'num particles (coulomb)'  'stat'  'good measurement'}
           units: []
    descriptions: []
      fieldnames: {'name'  'pulseId'  'x'  'y'  'tmits'  'stat'  'goodmeas'}
          values: [1x1 struct]
 
ans =
   -0.0466    0.4037   -0.5933    0.9624   -0.8016    0.9845   -0.0871    0.9946    0.3572    0.9041

Java Examples

example type

action

example

AidaPvaClient

import java.util.List;
 
import edu.stanford.slac.aida.client.PvaTable;
import org.epics.pvaccess.server.rpc.RPCRequestException;
 
import static edu.stanford.slac.aida.client.AidaPvaClientUtils.pvaRequest;
 
public class Example {
    public PvaTable getTable() throws RPCRequestException {
        return (PvaTable) pvaRequest("NDRFACET:BUFFACQ")
                .with("BPMD", 57)
                .with("NRPOS", 10)
                .with("BPMS", List.of("BPMS:LI02:501", "BPMS:DR12:334"))
                .timeout(30)
                .get();
    }
}

PvaClient

import org.epics.nt.NTURI;
import org.epics.pvaClient.PvaClient;
import org.epics.pvaClient.PvaClientChannel;
import org.epics.pvdata.pv.PVStructure;
 
public class Example {
    public PVStructure getTable() {
        String pvName = "NDRFACET:BUFFACQ";
 
        NTURI uri = NTURI.createBuilder()
                .addQueryInt("bpmd")
                .addQueryString("bpms")
                .addQueryInt("nrpos")
                .addQueryInt("timeout")
                .create();
        uri.getPath().put(pvName);
        uri.getQuery().getIntField("bpmd").put(57);
        uri.getQuery().getStringField("bpms").put("[\"BPMS:LI02:501\", \"BPMS:DR12:334\"]");
        uri.getQuery().getIntField("nrpos").put(10);
        uri.getQuery().getIntField("timeout").put(30);
 
        PvaClient client = PvaClient.get();
        PvaClientChannel channel = client.channel(pvName, "pva", 30.0);
        return channel.rpc(uri.getPVStructure());
    }
}

PvAccess

import org.epics.nt.NTURI;
import org.epics.pvaccess.client.rpc.RPCClientImpl;
import org.epics.pvaccess.server.rpc.RPCRequestException;
import org.epics.pvdata.pv.PVStructure;
 
public class Example {
    public PVStructure getTable() throws RPCRequestException {
        String pvName = "NDRFACET:BUFFACQ";
 
        NTURI uri = NTURI.createBuilder()
                .addQueryInt("bpmd")
                .addQueryString("bpms")
                .addQueryInt("nrpos")
                .addQueryInt("timeout")
                .create();
        uri.getPath().put(pvName);
        uri.getQuery().getIntField("bpmd").put(57);
        uri.getQuery().getStringField("bpms").put("[\"BPMS:LI02:501\", \"BPMS:DR12:334\"]");
        uri.getQuery().getIntField("nrpos").put(10);
        uri.getQuery().getIntField("timeout").put(30);
 
        RPCClientImpl client = new RPCClientImpl(pvName);
        PVStructure response = client.request(uri.getPVStructure(), 30.0);
        client.destroy();
        return response;
    }
}