Forum > Networking and Web Programming
OPC client with Lazarus
mig-31:
I think it will be better to release server/client for OPC UA. It is multi-platform . Do not need COM/DCOM.
Anyway mostly it better use MODBUS TCP to communicate with PCL and HMI devices. PascalScada project support it.
avra:
--- Quote from: mig-31 on August 08, 2013, 10:41:52 am ---I think it will be better to release server/client for OPC UA. It is multi-platform . Do not need COM/DCOM.
--- End quote ---
OPC UA specification is not free and available only to members. There isn't any free implementation even for Delphi. The day it shows for either Delphi or Lazarus will make me very happy. Till then, OPC DA is quite fine and working with current OPC servers.
--- Quote ---Anyway mostly it better use MODBUS TCP to communicate with PCL and HMI devices. PascalScada project support it.
--- End quote ---
That is all right if your device is also talking MODBUS. Although MODBUS is one of most widely used protocols there are thousands of others, and if you make your application OPC client instead of just MODBUS client, then you will be able to talk to almost any device (not just ones with MODBUS) since OPC servers exist for virtually all of them.
jl:
It has been 2 years and lots of new solutions are using OPC UA, just want to check with you guys if there's any endeavor on OPC-UA Client along the likes of the opcdelphi project? Thanks in advance. :)
avra:
--- Quote from: touchring on July 14, 2015, 08:36:42 am ---It has been 2 years and lots of new solutions are using OPC UA, just want to check with you guys if there's any endeavor on OPC-UA Client along the likes of the opcdelphi project?
--- End quote ---
There isn't FPC/LAZ solution yet. The good thing is that that there is now an open source solution in C at http://open62541.org. The bad thing is that no one with free time seams to be interested enough to convert it into Pascal. There is another C solution at http://www.openopcua.org, but unfortunately author allowed using it only as a library from Pascal - which makes it a worse candidate.
avra:
https://sourceforge.net/projects/myopcclient/?source=directory
OPC components now exist for Lazarus, too. Unfortunately GPL.
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