PLC Scan Time Benchmark

[Archie]

I posted this on another forum and found the results interesting so I thought I'd share them here. I ran a couple intensive tests on various PLCs to see how fast they could scan a program. The tests consist of a math and conversion, index text, bitwise test, and bubble sort. While running the code I checked the scan time to see how long it took the PLC to process it. Here are my results so far. Times are in milliseconds:

	MathTest	IndexTest	BitwiseTest	BubbleSort
Omron CP1H	2030.0			2350
Schneider M340	849.0	411	32	---
2080-LC20-20QBB (Micro820)	499.0	744	---	---
Siemens S7 151-8 CPU	430.0	609	307	---
CompactLogix L16ER v24	348.0	131	148	1398
CompactLogix L24ER	293.0
ControlLogix L71 v31	313.0	147	167	1570
AD Productivity P1-540	271.0			---
AD Productivity P2-550	264.2			---
Beckhoff CX8090	255.0			631
Click C0-11DRE-D	202.0			---
Omron NJ101-9000	84.0		11	82
ControlLogix L85E v32	9.5	3.5	2.4	77
Omron NX1P2-9024DT1	8.1	3.0	5.0
ControlLogix L85E v28	7.5	3.7	2.6	83
CompactLogix L306ER v32	7.3	3.4	2.4	78
Beckhoff CX9020 TC3	6.5	3.8	2.3	71
BrainBoxes BB-400/CodeSys 3.5.15	5.1	6.3	3.6	38
Beckhoff CX5140 TC3	4.2			11
Kunbus RevPi Connect+/CodeSys 3.5.14	2.5	3.1	1.8	33

Test Code in RSLogix Format
MathTest

Code: [Select]

Real1:=123;
Real2:=456;
FOR i:=0 TO 99999 DO
DINTResult:=(Real1*Real2);
END_FOR;

IndexTest

Code: [Select]

FOR j:=0 TO 9999 DO
  FOR i:=0 TO 9 DO
DINT1[i]:=DINT2[i];  (*'Arrays of 10 elements *)
  END_FOR;
END_FOR;

BitwiseTest

Code: [Select]

FOR i:=0 TO 99999 DO
DINTResult:=i AND 2730; (* '* Every other bit for 12 bits *)
END_FOR;

BubbleSort

Code: [Select]

Result[0]:=2;
Result[999]:=-1;

REPEAT
swapped:=0;
FOR i:=1 TO 999 DO
IF (Result[i-1]>Result[i]) THEN
Temp:=Result[i];
Result[i]:=Result[i-1];
Result[i-1]:=Temp;
swapped:=1;
END_IF;
END_FOR;
UNTIL (NOT swapped)
END_REPEAT;


[bachphi]

If I am not mistaken , RevPi is only 3B, not even 3B+ , yet it beat out  $16K L85E processor?

[Archie]

I did the test on a RevPi Connect+ , which uses the compute module 3+ that I think is the equivalent of the B+

I was surprised it was about 2.5 times faster the AB L8x processor (The latest quotes I got for power supply, rack, and L85E came in near $20k). I ran multiple tests with the RevPi as an Ethernet/IP slave to a CompactLogix and an EtherCAT master to Beckhoff IO. I even did some testing with it as a Modbus server communicating with AdvancedHMI. Handled it all with ease. For less than $500 for hardware and a CodeSys license, it really is a game changer.

[larryhts]

It would be interesting to see the Automation Direct P2-550 PLC or any of the Productivity Series PLC’s.
We are using them for our machines along with the Advanced HMI 10” TouchPanel.

[Archie]

It would be interesting to see the Automation Direct P2-550 PLC or any of the Productivity Series PLC’s.
We are using them for our machines along with the Advanced HMI 10” TouchPanel.

I ran the math test on a P2000 and added it to the results above. I'm not efficient at all with the editor, so I didn't convert the bubble sort. If you have time to convert the bubble sort to the ladder and post it, I can load it up and test it.

[Archie]

I added more to the list. The one I was surprised about was the L306ER CompactLogix. I did not expect it to be faster than the L85E ControlLogix

[PLCGrub]

Hi All,

Stuck in Isolation so what the heck

Just ran the maths on the P1-540 productivity 1000 with an average of 271msec,
and the Click C0-11DRE-D average of 202msec

Once I work out the other tests I will add those results

[Archie]

Just ran the maths on the P1-540 productivity 1000 with an average of 271msec,
and the Click C0-11DRE-D average of 202msec

Thank you for the additions. I added them to the list

[PLCGrub]

Hi,

I had a quick play with a 2080-LC20-20QBB (Micro820):

Maths Test - 499ms
Index Test - 754ms

[Archie]

Hi,

I had a quick play with a 2080-LC20-20QBB (Micro820):

Maths Test - 499ms
Index Test - 754ms

Thanks for the additions. I added it to the list.