fix(inputs.s7comm): Fix bit queries

[phagemann]

• Updated associated README.md.
• Wrote appropriate unit tests.
• Pull request title or commits are in conventional commit format

resolves #14043

Update Gos7 to allow query of bits. Enforce valid range (0-7).

[Hipska]

Do you think it will take long before robinson/gos7 will be patched?

[phagemann]

Working on a PR to fix this.
Honestly i am not sure about the time schedule. Maybe a month.

At least 2b34129 is necessary anyway.

[Hipska]

Can you mark specifically what needs to be reverted when the fix is released upstream?

[phagemann]

Both needs to be changed back to 0x01:

telegraf/plugins/inputs/s7comm/s7comm.go

Line 43 in f4c56e1

"X": 0x01, // Bit

telegraf/plugins/inputs/s7comm/s7comm_test.go

Line 260 in 0c1e213

WordLen: 0x01,

Commit 30a5940 and c28e49b would need to be reverted.

[Hipska]

Please mark that in the code. (If @srebhan agrees to that)

[srebhan]

@phagemann I would love to see this fixed upstream in gos7 and then change this PR to change whatever is necessary (and update the gos7 version). The problem with temporary fixes is that nobody will remove them once they are in. ;-)

Can you fix this upstream? I've created some PRs there and usually they are quick in merging that stuff...

[phagemann]

That's fine with me.

I will do the upstream fix and come back afterwards 😃.

[powersj]

@phagemann it looks like your upstream issue was closed due to your fix in robinson/gos7#65

Are we good to update the version of s7comm instead of this PR now?

[Hipska]

@powersj he stated that the PR would still be needed:

Working on a PR to fix this. Honestly i am not sure about the time schedule. Maybe a month.

At least 2b34129 is necessary anyway.

[powersj]

Then the title and commit message need to be updated, @phagemann needs to confirm my original question, and afterwards we can re-review

[phagemann]

@powersj In order to solve this, I need to adjust the MR. Just updating won't work. Shouldn't be much work, but I would like to test it on a real system. If everything works well, I will have one available by the end of the week.

@phagemann it looks like your upstream issue was closed due to your fix in robinson/gos7#65

Are we good to update the version of s7comm instead of this PR now?

[GitTurboy]

Download PR build artifacts for linux_amd64.tar.gz, darwin_amd64.tar.gz, and windows_amd64.zip. Downloads for additional architectures and packages are available below.

👍 This pull request doesn't change the Telegraf binary size

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Thank you all, but I found the fix made to resolve【Allow PDU-size to be set as config option】 problem（ https://github.com/influxdata/telegraf/pull/14045） were not included

[srebhan]

@phagemann looks good overall, only two minor comments from my side...

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_amd64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

👍 This pull request doesn't change the Telegraf binary size

📦 Click here to get additional PR build artifacts

Artifact URLs

DEB	RPM	TAR GZ	ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz

[GitTurboy]

I tried to use the last PR(telegraf-1.29.0~92c29c75_windows_amd64) to fetch about 90 items data from a smart 200 PLC, the log shown error message as below:[ I set pdu_size = 200]
[inputs.s7comm] Error in plugin: reading batch 1 failed: CLI : too may items (>20) in multi read/write

[phagemann]

The error message is produced by Gos7. You should not exceed a pdu-size of 20. This is the maximum number of elements contained in a request batch. It does not limit the number of total items. Please try to set set it back to 20 or lower.

I tried to use the last PR(telegraf-1.29.0~92c29c75_windows_amd64) to fetch about 90 items data from a smart 200 PLC, the log shown error message as below:[ I set pdu_size = 200] [inputs.s7comm] Error in plugin: reading batch 1 failed: CLI : too may items (>20) in multi read/write

[GitTurboy]

The error message is produced by Gos7. You should not exceed a pdu-size of 20. This is the maximum number of elements contained in a request batch. It does not limit the number of total items. Please try to set set it back to 20 or lower.

I tried to use the last PR(telegraf-1.29.0~92c29c75_windows_amd64) to fetch about 90 items data from a smart 200 PLC, the log shown error message as below:[ I set pdu_size = 200] [inputs.s7comm] Error in plugin: reading batch 1 failed: CLI : too may items (>20) in multi read/write

But when I set pdu-size to 20 , the message in log will shown:

2023-11-13T00:19:27Z D! [inputs.s7comm] Reading batch 1...
2023-11-13T00:19:27Z E! [inputs.s7comm] Error in plugin: reading batch 1 failed: CPU : total data exceeds the PDU size

[phagemann]

Now your CPU (smart 200) complains about the pdu-size beeing too large. Try lowering it, until the CPU stops reporting this error.

Not sure, whether this is this the right place, as it referring to a already closed issue. It is not relevant for this MR.

[GitTurboy]

Now your CPU (smart 200) complains about the pdu-size beeing too large. Try lowering it, until the CPU stops reporting this error.

Not sure, whether this is this the right place, as it referring to a already closed issue. It is not relevant for this MR.

Thanks， this method resolved the problem.

[srebhan]

Thanks for fixing this @phagemann!