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gijzelaerr / python-snap7

A Python wrapper for the snap7 PLC communication library
http://python-snap7.readthedocs.org/
MIT License
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Feature request: ReadSZL() #196

Closed NicklasMD closed 3 years ago

NicklasMD commented 3 years ago

Hi I didn't know where the right place where to ask for this? The Snap7 has a function to read SZL values or lists of values, I would like that also in the Python-Snap7 Thanks for all your work.

Example from the Snap7 documentation: Cli_ReadSZL Description Reads a partial list of given ID and INDEX. Declaration int Cli_ReadSZL( S7Object Client, int ID, int Index, TS7SZL pUsrData, int Size); function Cli_ReadSZL(Client : S7Object; ID, Index : integer; pUsrData : PS7SZL; var Size : integer) : integer; Parameters Type Dir. Client Native Integer In The handle as return value of Cli_Create(), passed by value. ID integer 32 In List ID Index integer 32 In List Index pUsrData Pointer to struct in Address of the user buffer size Pointer to integer 32 In Buffer size available Out Bytes rea

swamper123 commented 3 years ago

What is an SZL btw? Never heared of that thing in an SPS context before (or can't remember).

This feature is actually not implemented, but feel free to make a PR. I would recommened that you check other functions/methods and adapt their "wrapping behaviour".

NicklasMD commented 3 years ago

The SZL's are used to get diagnostic data out of the PLC For example status on the fieldbus, diagnostic buffer, status LED's etc. so I think it's a quite useful feature.

I'm not sure I'm competent enough to make the feature myself...

swamper123 commented 3 years ago

Found out SZL means "SystemZustandsListe", so like you said a diagnostic datas.

I thought I may never contribute to this repo as well, but after a while I am pretty into it in any kind of way. 😄
If you inspect other client requests of their structure, you'll see that they are pretty similar and you see where self.library.... is used, that this is the actual C command.

Otherwise you may have to wait a longer time until somebody implements it or you have to make PLC workarounds.

lautarodapin commented 3 years ago

I really would love that two, I was looking for something like that for checking if devices where connected Didn't know that szl was the option I will check if i can't get to something