Perle Systems STS, SCS manual UDP Unicast Format, UDP Broadcast Packet

I/O UDP

I/O UDP

Industrial applications often monitor the status of I/O devices such as sensors, alarms, relays, etc. by polling for I/O data. The IOLAN’s I/O UDP feature can help to minimize network traffic by broadcasting I/O status to industrial applications on specified intervals, providing I/O status in a timely manner.

The IOLAN’s I/O UDP broadcast feature sends the status of attached I/O devices to defined hosts on the network. Depending upon the IOLAN model and the configuration of the I/O channels, the UDP packet contains the current status and/or data of each enabled I/O channel or serial pin signal.

UDP Unicast Format

PC applications must be able to interpret the UDP packet to obtain I/O channel status and data. This section provides the detailed structure of the UDP datagram and its data format.

UDP Broadcast Packet

Version (1 Byte)

Total Packet Length

(2 Bytes)

Analog Section

Digital/Relay Section Serial Pin Signal Section

Each section, with the exceptions of the Version and Total Packet Length sections, is comprised of its own subset of bytes.

Note: All 2 byte values are in big Endian (network) order. All 4 byte values are IEEE 754 single precision floating point numbers in big Endian (network) order.

zVersion—The current version of the format of I/O UDP broadcast packet.

zTotal Packet Length—The total length of the UDP packet.

zAnalog Section—The Analog Section of the UDP packet, which contains data/status of the Analog I/O channels. The Analog Channel Data subsection (within the Analog Section) will only exist if the channel(s) is enabled.

zDigital/Relay Section—The Digital/Relay Section of the UDP packet, which contains status of Digital and Relay I/O channels. The Channel Data subsection within the Digital/Relay Section will always be present.

zSerial Pin Signal Section—The Serial Pin Signal Section of the UDP packet, which contains the status of the IOLAN’s serial port’s control signal pins. The Serial Pin Signal Data subsection within the Serial Signal Pins Section will always be present.

264 IOLAN SDS/SCS/STS User’s Guide, Version 3.6