Re: How to configure waveform record to read remote PV via PVAccess in EPICS

["Sukhanov, Andrei via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Varuna,

Here is an example how to create and modify waveform PV sourced from remote PV using python p4p:

import time

import numpy as np

from p4p.server.thread import SharedPV

from p4p.server import Server

from p4p.nt import NTScalar

from p4p.client.thread import Context

ctxt = Context('pva')

# create output PVs, if needed

pv = SharedPV(nt=NTScalar('ah'), initial=[0])# int16 array

# callback function to double the input array

def callback(V):

      ar = np.array(V)

      pv.post(np.array(V)*2)

callback = ctxt.monitor('epicsDev0:c01Waveform', callback)

with Server(providers=[{'my:array': pv}]):

      while True:

            # do something else or sleep.

            time.sleep(1)

/Andrey

---

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Varuna Crishan Meddage via Tech-talk <tech-talk at aps.anl.gov>
Sent: Wednesday, March 25, 2026 3:13 PM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: How to configure waveform record to read remote PV via PVAccess in EPICS

 

I am trying to create a waveform record in my IOC that takes its values from a remote PV hosted on another serverusing EPICS PVAccess (PVA). Here’s what I want to achieve: Define a waveform record locally (e. g. , LOCAL: WF) Subscribe to a remote

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I am trying to create a waveform record in my IOC that takes its values from a remote PV hosted on another serverusing EPICS PVAccess (PVA).

Here’s what I want to achieve:

• Define a waveform record locally (e.g., LOCAL:WF)
• Subscribe to a remote PV (e.g., REMOTE:ARRAY:PV) on a server with a known IP address and port
• Automatically update the waveform at a set scan rate

I am unsure about the exact configuration. Specifically, I would like guidance on:

1. Waveform record DB definition – how should the DTYP and INP fields be set to read from the remote PV?
2. Specifying the server IP and port in the INP field.
3. Specific DBD files and libraries that need to be included to achieve this goal.
4. Any pitfalls, such as array size (NELM) matching or data type requirements.

For example, would a record like this work?

=================================================

record(waveform, "LOCAL:WF") {

    field(DTYP, "pvaClientWaveform")

    field(INP, "PVA:REMOTE:ARRAY:PV@10.200.34.12:5075")

    field(SCAN, "1 second")

    field(NELM, "4096")

}

===============================================

I would greatly appreciate any example .db record, IOC DBD configuration, or startup instructions for properly using a remote PV with waveform records via PVA.

My base EPICS version is : epics-base-R7.0.9-328

Thanks

Varuna Meddage