MODBUS Performance

MODBUS/TCP Ethernet communication

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:Q02HCPU
Communication unit:QJ71MT91
Register：400001-408192(D0-D8191)
Max scan time:0.4msec

Communication Performance

(sec)

	1024	2048	4096	8192	16K	32K	64K	128K
Average	0.134	0.272	0.533	1.041	2.087	4.155	8.399	16.728
Max	0.151	0.282	0.643	1.069	2.141	4.311	8.504	16.843
Min	0.130	0.251	0.451	0.989	2.033	4.081	8.312	16.618

Results

In case of continuous Data Register(D), it is possible to get max 8,000 points per sec.

Comment

*Graph displays average time of ten times measurement.(1point = 1word)
*In case of 16K points access , Read 16K points by using 2 devices.( 8K point per 1 device).
*The result only means our examination, it doesn't guarantee performance.

[Jun 2010]