Technical information

3/15
Modicon M580 automation
platform
Ethernet Modbus/TCP network
Performance
Application response time
Modbus (or Uni-TE) messaging service response time
Exchanges between the PLC CPU and the Ethernet module are synchronous with
the PLC scan cycle time (CT), just like the I/O exchanges. When an event occurs
(such as an input being set to 1 for example), a message can be transmitted only
after this input has been taken into account (start of the next cycle) and the PLC
(Modicon M340, Modicon Premium, or Modicon Quantum) program has been
executed, i.e. on average approximately 1.5 cycles after the event occurred.
The network access time (NAT) shown in the table below in ms is a total of the
module transit time and the delay before the message can be transmitted on the
network.
Processing
Modbus TCP/IP
message
requests
Modicon M580 BMEP58 Modicon M580 BMX Modicon M340 BMX Modicon Premium TSX Modicon Quantum 140
1020
2020
2040
3020
3040
4020
4040
NOC0402 (1) NOC0401 P342020
P342030
ETY210
ETY110WS
ETC101
WMY100
P5710...57 60
NOC77101/78
ppp
CPU113/311pp
CPU434/5341p
CPU65ppp
CPU67ppp
NOC77101
NOC78p00
Network
access time
(NAT)
< 10 ms < 10 ms < 10 ms < 10 ms < 10 ms < 25 ms < 10 ms < 10 ms < 10 ms
The transaction time TT includes the delay between the transmission of a message
from a client (station 1), its reception by the server (station 2), processing the
request, sending back the response, and it being taken into account by the station 1
(updating an output for example).
As the block diagram above shows:
b The transaction time TT will be between:
2
x CT1 + 2 x NAT < TT < 4 x CT1 + CT2 + 2 x NAT
b The average duration TT
av
is equivalent to:
TT
av
= 3 x CT1 + 0.5 x CT2 + 2 x NAT
(1) The BMXNOC0402 communication module will be replaced by the BMENOC03p1 modules
during the 2nd quarter of 2014.
Performance (continued)
Modbus messaging service response time
Station 1
Event
CT1
NAT NAT
CT2 CT2 Station 2
Report
TT
CT1 CT1 CT1
Action
Processors:
page 1/18
I/O architectures:
page 2/2
Software:
page 4/2
Ruggedized Modicon M580
modules: page 5/2
2
1
3
4
5
6
7
8
9
10
2
1
3
4
5
6
7
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10