SIEMENS SIMATIC Performance

SIMATIC-S7 series Ethernet connection

Add array OPCItems as Advise from a OPC Client.
It is measured reading time from added OPCItems. Communication performance is defined as average time of ten times measurement.
This time means to read the value of a continuous area of the device.

PC specification

OS:
    Windows 7 Professional  32bit OS
CPU：
    Intel(R) Core(TM) i7 CPU 860 @2.80GHz
Memory：3.00GB
OPC Server：
    DeviceXPlorer OPC Server Ver4.2.0.2
OPC Client：
    OPCClient sample VcSampleOpc(C++)
Cable：
    100BASE-TX cross cable connecting directly

OPC Server setting

Protocol Timer Tick：10msec
Timer Tick for Async Update Mode：10msec
Multi Access Mode：Enable
Multi Access for Snyc Asnyc：Disabled
Async Update Mode：Disabled

PLC setting

CPU:CPU315
Communication unit:CP343
Register:DB1:0-DB1:8191,DB2:0-DB2:8191,DB3:0-DB3:8191,DB4:0-DB4:8191
Max scan time:1msec

Communication Performance

≪CP343≫

(sec)

	1024	2048	4096	8192	16K	32K
Average	0.182	0.368	0.724	1.427	2.843	5.703
Max	0.190	0.380	0.765	1.461	2.882	5.733
Min	0.172	0.360	0.700	1.412	2.811	5.653

≪Built-in Ethernet≫

(sec)

	1024	2048	4096	8192	16K	32K
Average	0.050	0.100	0.190	0.370	0.742	1.486
Max	0.050	0.101	0.191	0.370	0.743	1.489
Min	0.050	0.100	0.190	0.370	0.741	1.477

Results

In case of Ethernet unit, to access continuous Data Block(DB), it is possible to get max 6,000 points per sec.
In case of Built-in Ethernet, to access continuous Data Block(DB), it is possible to get max 20,000 points per sec.
CPU Built-in Ethernet is about three times as earlier as the Ethernet unit.