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Klinkmann Automation Unitronics Vision Server
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UDP MODBUS/IP+LRC – The same as TCP MODBUS/IP+LRC protocol with exception
that UDP is used instead of TCP. The protocol is meant to cooperate with programmable
wireless modem (e.g. Siemens TC65T/Java terminal) connected to UNITRONICS PLC
serial port in case the Modbus checksum is not calculated inside modem embedded
application.
Note: if UDP is used and messages in protocol do not contain transaction ID, that can be
a reason for some kind of mismatches in case of slow or loaded GPRS communication.
Remote Client IP Address field is used to specify the IP address of client (PLC), only
from where the connection will be accepted. Not always this IP address is known – for
example, in GPRS public network the IP address for client (GPRS-modem+PLC) is
assigned by GPRS Access Point dynamically and it is different at each connection, so for
such cases the ID String should be used to identify the PLC. If Remote Client IP
Address is empty then connection will be accepted from any IP address.
Note!
If both ID String and Remote Client IP Address fields are empty then VISION Server
will not wait for ID String and accepts any new connection on IP Port. In this case each
Node should have unique IP Port number, otherwise any new connection on same IP
Port will destroy the previous connection.
The following table illustrates possible ID String and Remote Client IP Address
variations and recommended implementations:
ID
String
-
+
+
Remote Client
Recommended implementation
IP Address
Point-to-point wired or GPRS connection. Each Node
has unique IP Port number.
+
Wired or GPRS (corporate network) connection where
each PLC (or “bridge” PLC) has a fixed IP address.
Several Nodes can have same IP Port number.
GPRS connection (public network) where each PLC (or
“bridge” PLC) has not a fixed IP address. Several
Nodes can have same IP Port number.
+
GPRS connection (corporate network) where each PLC
(or “bridge” PLC) has a fixed IP address. Using ID
String can improve the reliability of system. Several
Nodes can have same IP Port number.
Unitronics Vision Server Ver 3.x User Manual Rev2.6
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