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An examination of plc performance.

Created by: Msorich at: 1/21/2020 4:11 PM (15 Replies)

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1/21/2020 4:11 PM	Rate (0)
Msorich Gold Member Joined: 6/28/2017 Last visit: 12/20/2022 Posts: 661 Rating: (37)	Hello everyone, did anyone ever make test-blocks which are capable to load or stretch gradually plc cycle in order to see its behaviour when it is artificially loaded? Some kind of benchmark test, so to speak. Could anyone suggests anything? Msorich
	Last edited by: Msorich at: 01/21/2020 16:19:47
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1/30/2020 1:00 PM	Rate (0)
Unreality Bronze Member Joined: 9/9/2014 Last visit: 1/25/2023 Posts: 237 Rating: (39)	Hi Well look, When I did the tests I did so ... Used 1000 instructions of multiplication and division of numbers like REAL. Then - created the FC block, on the basis of SCL Thousands of instructions were crammed into it. Further, through the asynchronous OB, this FC was called. But since this is not enough for a real PLC. I made several calls to this block inside OB That is, i made about 500 entries, each occurrence was controlled by a bit or another variable (bit). There was an algorithm that after one FC, as many FCs are processed as needed, from one to 500 - thereby making different cycle times. It’s all just for testing the operation inside the PLC, without checking the connections with third-party devices - it’s still trickier there, but I didn’t do it ...
	Best Regards PMA
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1/31/2020 10:16 AM	Rate (3)
smiffy Platinum Member Joined: 1/17/2007 Last visit: 1/24/2023 Posts: 1516 Rating: (513)	I did a suite of benchmark tests for comparing Siemens CPU's to Allen-Bradley CPU's. They are written in SCL. They are a mix of, logic operations, integer arithmetic, floating point arithmetic, systems calls, math functions, 2D and 3D table interpolation. Each mark is timed and the results are logged. Attachment BenchMark.zip (232 Downloads)
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/2/2020 5:09 PM	Rate (0)
Msorich Gold Member Joined: 6/28/2017 Last visit: 12/20/2022 Posts: 661 Rating: (37)	smiffy They are written in SCL. smiffy thank you for useful upload, I'm trying to launch this FB on my bench and TIA portal yells at count and CDT. So my question is what the beasts they are in modern TIA's implementation? Msorich
	Last edited by: Msorich at: 02/03/2020 07:14:02
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2/3/2020 11:34 AM	Rate (2)
smiffy Platinum Member Joined: 1/17/2007 Last visit: 1/24/2023 Posts: 1516 Rating: (513)	These were written for STEP7, so they will need some rewriting for TIA. The benchmarks themselves are fine, it is just the calling / time logging that requires some attention. They also require a timed setting of the count variable to 1. This is the signal for the running of the benchmark to be suspended the time logged. So count should be a memory marker. Them setup another bit of code that sets the count variable to 1 if it is 0. This code will be run in your test time OB (say 1 second). So the sequence is. 1) You set RUN_BM to an value in the 1 to 10 range depending on which benchmark you want to run. 2) The selected benchmark will now run, and continue to run until count is set to a value greater than 1 3) After a set time period, the timed OB (your test time), will run and set the value of count to 1. 4) This will cause the benchmark to stop running, and the time will be logged. You can now repeat it for whichever benchmark you require.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/3/2020 12:04 PM	Rate (0)
Msorich Gold Member Joined: 6/28/2017 Last visit: 12/20/2022 Posts: 661 Rating: (37)	Everything becomes a bit clearer, The point is I can't even look at FB's exterior view, since compilator refuses to compile that code. Are there any successors of count and CDT in TIA portal. As I understood they are not simple variables. Am I correct? Msorich
	Last edited by: Msorich at: 02/03/2020 12:05:22
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2/3/2020 12:14 PM	Rate (0)
smiffy Platinum Member Joined: 1/17/2007 Last visit: 1/24/2023 Posts: 1516 Rating: (513)	count is a simple integer. CDT is a DATE_AND_TIME type and used to obviously, contain data and time information.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/3/2020 12:22 PM	Rate (0)
Msorich Gold Member Joined: 6/28/2017 Last visit: 12/20/2022 Posts: 661 Rating: (37)	smiffy count is a simple integer. CDT is a DATE_AND_TIME type and used to obviously, contain data and time information. I've asked because they are not being perceived by TIA as #local vars. Msorich Attachment view.png (200 Downloads)

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2/3/2020 12:52 PM	Rate (0)
smiffy Platinum Member Joined: 1/17/2007 Last visit: 1/24/2023 Posts: 1516 Rating: (513)	I have already told you that 'count' is a memory marker. It has to be as it is used by the benchmark OB and also the timed OB. Also, the parameter for the date and time input to the RD_SYS_T function is not CDT, it is OUT (CDT is the parameter name for the READ_CLK function on STEP7). So it looks to me like you correctly changed READ_CLK to RD_SYS_T as part of your porting, but failed to notice that the parameter name has changed. If you change the code to #RetVal := RD_SYS_T(OUT := #TheTime); it should be OK I think.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/3/2020 2:21 PM	Rate (0)
Msorich Gold Member Joined: 6/28/2017 Last visit: 12/20/2022 Posts: 661 Rating: (37)	smiffy I have already told you that 'count' is a memory marker. It has to be as it is used by the benchmark OB and also the timed OB. concerning count, It can not be an usual memory marker, since we are speaking about FB, it can be either local static var, or local temp var, or Input var, or Output var. Otherwise no success, smiffy. Also what about log? Log is also not defined. Attachment log.png (178 Downloads)

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