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Why OPC communication is so slow?

Created by: pandora303 at: 1/30/2008 9:17 AM (6 Replies)

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1/30/2008 9:17 AM	Rate (0)
pandora303 Advanced Member Joined: 1/26/2007 Last visit: 6/17/2020 Posts: 14 Rating: (0)	I have Simotion C230 and 4 servo axis in my system. My Delphi application uses Kassl dOPC as OPC Client and Simatic Net 6.4 as OPC server. Communication interface is ethernet. My problem is slow communication especially writing item. I just write 3 Boolean and 1 integer value with WriteSync. Also actual positions of servo axis changes slowly on the screen. My questions are below. 1) What is the effect of DP cycle time on OPC communication speed. Does the aim is as small as possible? (I checked "Activate constant cycle time" and it is 1.75 ms) 2) Should I check Slave synchronization in Profibus options? 3) Does Background Time Allocation effects OPC communication speed? (In my project Background Time is 5 servo cycle clocks) 4)Is it a problem because of Simatic Net? 5)Is there any way to test speed? 6)What can be the problem? Sorry for my bad English...

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1/30/2008 2:49 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Hello, I just wonder... do you connect to the PLC with a CP 5611 over PROFIBUS DP Interface? If so, do you use DPas Busprofile? If so, please change it to Standard because DP is only for DP Monomaster communication and as you do S7 Communication too DP is not recommendable. Does the change in the Busprofile, and the download of the HW Config affect the Communication? Please do not forget the change and download the HW Config of the PC Station too. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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1/30/2008 4:10 PM	Rate (0)
pandora303 Advanced Member Joined: 1/26/2007 Last visit: 6/17/2020 Posts: 14 Rating: (0)	In my configuration there is an industrial PC and my Delphi application runs on it. PC connected to Simotion via Ethernet port (no communication card such as CP5611). There are 4 drives (Simodrive 611U) and an I/O card (6FC5611 0CA01 0AA0) connected to Simotion via Profibus. I try to increase constant DP cycle time but nothing changed. Also I tried to change Background Time Allocation (16 Servo Cycle Clock) speed increased just a little but still slow. I don't know where should I check.

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1/30/2008 4:23 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Hello, I am sorry... but if you are connected over Ethernet the PROFIBUS is usually no issue. So if you still are not able to access the data in the system fast enough I fear this is something only the SIMOTION specialists can say something about. I have to admit I have no clue about the surrounding conditions on this. I will try to get the Administrators to forward your Question to the SIMOTION Forum... Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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1/31/2008 4:01 PM	Rate (0)
pandora303 Advanced Member Joined: 1/26/2007 Last visit: 6/17/2020 Posts: 14 Rating: (0)	Is there anybody here who can help me?

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2/6/2008 10:31 AM	Rate (0)
pandora303 Advanced Member Joined: 1/26/2007 Last visit: 6/17/2020 Posts: 14 Rating: (0)	I try SimaticNET 6.3 instead of SimaticNET 6.4 and speed is better.

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2/6/2008 11:17 AM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Hello, This is Strange but I am happy that the System runs now more like the way you planned. Did you install the SPs and HFs available for the Version 6.4? Please do not forget, never change a running system. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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