Read counter

ALI — Fri, 06 Mar 2026 22:43:32 -0000

If the library is updated to include built-in methods for reading and writing counters and handling timers, that would make development much easier for people working with S7 PLCs. Counters are a common part of industrial logic, and having a direct function instead of manually decoding BCD values would simplify the code a lot. It’s similar to how a number Counter works in general software—once the value is properly converted and exposed by the library, developers can simply read and display it without worrying about the underlying format.

S71512 Read DB

Mauro Ruby — Mon, 09 Feb 2026 21:02:08 -0000

Assicurati che la DB non sia ottimizzata e che sia abilitato nel PLC "GET" e "PUT"

BlockInfo not correct Code and Interface timestamps

Anandhakumar Palanisamy — Fri, 13 Jun 2025 10:01:05 -0000

Dear @Davide Nardella,

I have fixed this issue in the C++ part of the source code, since timestamp information was required for scenario.

Changes related to the fix : https://github.com/Securenok/snap7/pull/2

In the c++ version of the library -> added two new fields, char CodeDateTime[25]; and char IntfDateTime[25];, to the structs TS7BlockInfo and PS7BlockInfo.
Added a helper function TSnap7MicroClient::FillDateTime(word SiemensDay, u_int SiemensMs, char *PTime) to fill the full timestamp information of the memory blocks to the newly added fields CodeDateTime and IntfDateTime.

The fixed version is made available for public use : https://github.com/Securenok/snap7

Kindly let me know if you find any issues with the above mentioned changes.

Thanks & regards,
Anand

LabView Random 0xC000005 App Crashes

Jacek Jemielity — Mon, 14 Apr 2025 13:32:24 -0000

Hi,
Has anyone experienced similar problems in Win11 that do not occur in Win10? The most frustrating thing is that this problem is not being reported online, as if I were the only one struggling with it.

Possible causes of random errTCPDataReceive

Davide Nardella — Fri, 21 Mar 2025 07:11:56 -0000

If you don't have an empty PLC, ask the PLC programmer to skip OB1 for some minutes and connect your PC directly to the PLC PN Port.

Possible causes of random errTCPDataReceive

Davide Nardella — Fri, 21 Mar 2025 07:07:31 -0000

Currently, it is set to 2000. Increasing it obviously improves the situation

this is not good news, if at 2000ms you have more problems than 3000ms it means that, statistically, some transaction takes 2500ms, and this is unacceptable.

In our high productivity lines we use Snap7 (of course ;-) ) and the maximum time we record is 500ms for a complete transaction (PLC->SQL->Feedback to PLC) in a wired network, more than that we cannot tolerate.

10/15 ms is the maximum time you should expect.

Possible causes:
1- PLC very congested (you can do little about it)
2- Network very congested (check topology, bottlenecks etc..)
3- Problem on cables (it happens sometimes, try changing them)
4- Problem on a switch (try moving the cables to another path)

For problems 3 and 4 you can use WireShark to see if there are TCP packet errors.

The protocol, apart from the PDU negotiation, is quite simple and is based on TCP/IP, you send the request and wait for the response.

If the time is high, either the transmission medium is compromised or the device is congested.

If you want to remove any doubts about the software and if you have the possibility, connect your software to an empty PLC in a controlled network (PC-Switch-PLC) and check the times.

Let me know.

Possible causes of random errTCPDataReceive

Stop81 — Thu, 20 Mar 2025 20:30:49 -0000

I masked the problem as suggested, but since I log every time it disconnects, I would like to address the root causes if possible. How can I act on the communication priority to avoid timeouts? Also, what is a good value for the readtimeout parameter in the msgSocket class of sharp7? Currently, it is set to 2000. Increasing it obviously improves the situation, but I want to avoid any unwanted side effects. Thanks for the suggestions!

Possible causes of random errTCPDataReceive

Stop81 — Thu, 20 Mar 2025 20:30:07 -0000

Possible causes of random errTCPDataReceive

Davide Nardella — Thu, 20 Mar 2025 11:44:31 -0000

Hi Laura,
These problems are also common in WinCC, it seems that they depend on the communication queues inside the PLC that have become very complex over time.

You can act on the communication priority, but it depends on the use you make of your automation, it may not be the most efficient way. (In my opinion, the communication load should never affect the CPU cycle time)

Or, as WinCC does, you can mask the problem: in case of TCP error, disconnect the client, then at the next turn of your communication loop, if you are disconnected reconnect and then read/write.

Attached the schematic loop.

Possible causes of random errTCPDataReceive

Laura Ferrari — Thu, 20 Mar 2025 09:40:24 -0000

Good morning, I am using the Sharp7 class in a read and write loop. The connection to the PLC is via Wi-Fi (but I have also tried directly with a cable). Occasionally, sometimes every 10 minutes and sometimes more frequently, I receive the code S7Consts.errTCPDataReceive because it times out in the WaitForData method. I have turned off the firewall. What else can I check?

Recent posts to Discussion

Read counter

S71512 Read DB

BlockInfo not correct Code and Interface timestamps

LabView Random 0xC000005 App Crashes

Possible causes of random errTCPDataReceive

Possible causes of random errTCPDataReceive

Possible causes of random errTCPDataReceive

Possible causes of random errTCPDataReceive

Possible causes of random errTCPDataReceive

Possible causes of random errTCPDataReceive