Re: [SPAM] Re: the least EPICS_CA_MAX_ARRAY used for EIGER2 4M detector

[Zhibang Shen via Tech-talk <tech-talk at aps.anl.gov>]

Thank you for your help, now we are updating EPICS base to version 7.0.9. It works perfectly now.

Zhibang

-----原始邮件-----
发件人: "Johnson, Andrew N." <anj at anl.gov>
发送时间: 2026-02-27 18:10:38 (星期五)
收件人: "shenzb at ihep.ac.cn" <shenzb at ihep.ac.cn>, "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov>
主题: [SPAM] Re: the least EPICS_CA_MAX_ARRAY used for EIGER2 4M detector

If your IOC and CA client(s) were built using any EPICS 7.0.x release, EPICS_CA_MAX_ARRAY_BYTES is optional, and will be ignored unless your site has explicitly set EPICS_CA_AUTO_ARRAY_BYTES=NO (described in that link). 

The elimination of these buffer-size issues is a good reason to update your EPICS Base version, especially where you’re dealing with large image data buffers.

- Andrew

-- 

Complexity comes for free, Simplicity you have to work for.

On 2/27/26, 9:16 AM, "Tech-talk" <tech-talk-bounces at aps.anl.gov> wrote:

Hi,

I am facing a problem with EPICS_CA_MAX_ARRAY_BYTES while using ADViewer monitoring Eiger2 4M detector.

I have followed the installation instruction of ADEiger and it works well. But if I set EPICS_CA_MAX_ARRAY_BYTES=10,000,000, ADViewer reports the exception of pendIO timed out. I also followed the troubleshooting to see whether all the configuration are properly set. The ArrayCallback PVs of cam1: and image1: are both set to Enable, and EPICS_CA_MAX_ARRAY is set to 40,000,000. I also tried EPICS_CA_MAX_ARRAY_BYTES=100,000,000 but it does not work either.

The pixel number of Eiger2 4M detector is 2068x2162=4,471,016. And the image bit depth is set to 32. I think the least EPICS_CA_MAX_ARRAY should be 2068x2162x4=17,884,064, then EPICS_CA_MAX_ARRAY_BYTES=40,000,000 should work. But it doesn't. I don't know why.

Could someone help me with this issue? Thanks in advance for any help.

Best regards,

---

Zhibang Shen

Institute of High Energy Physics, Chinese Academy of Sciences

19B Yuquan Road, Shijingshan District, Beijing, China

100049