Connection To The Customer Control System; Udp/Tcp Process Data Protocol; Introduction - Balluff BVS ID-M1280 F1 Serie Konfigurationsanleitung

BVS ID-M1280xF1-xx-xxx
4

Connection to the customer control system

4.1

UDP/TCP Process Data Protocol

4.1.1 Introduction

It is possible to control BVS ID using UDP sockets or TCP sockets via the Ethernet interface of the host system.
For this, the port 36701 is used.
TCP and UDP sockets are essentially different. With a TCP socket first a connection between BVS ID and the
controlling system is opened. With a UDP socket this is not necessary since individual packets are simply sent.
In both cases BVS ID expects a Connect message, then it starts to send out status updates and result data. If
the controlling system does not want any more updates, it sends Disconnect. Likewise, a Disconnect should be
sent before the socket is closed. BVS ID supports only one active client.
BVS ID responds to a Connect message with a Connect response; in addition, it then sends a status message
to the controlling system so that the latter is informed about the status of BVS ID.
Since TCP is based on data streams, multiple messages sent by BVS ID may share a common TCP-header. It
is therefore recommended to parse the user data length, which is sent with every message, to divide individual
messages on the receiver side. To minimize latencies, Nagle's algorithm is deactivated in BVS ID (option
TCP_NODELAY). It is recommended to set option TCP_NODELAY in the controlling system also. In many cases
this also prevents that multiple messages share a common TCP header.
Since UDP is based on data packages, every message of BVS ID corresponds exactly to one UDP message.
On the other hand, UDP provides no guarantee, that sent messages are delivered. If transmission security is of
great importance, use of TCP sockets is therefore recommended.
Invalid messages are ignored by BVS ID.
 NOTE
To communicate via UDP, you have to set the Mode in the system menu ("System settings -> Process
Communication") to "UDP". To communicate via TCP, the Protocol must be set to "TCP".
Messages from BVS ID are sent asynchronously.
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