K-Patents PR-33-AC - Manual (Page 44)

38 PR-33-AC instruction manual
Document/Revision No. Rev. 1.02 Effective: June, 2014
9 Ethernet protocol specification
The main purpose of the Ethernet connection is to collect measurement data from the
instrument. For this data acquisition, you’ll need to have suitable software on your
computer. You can program a data acquisition program yourself following the specifi-
cations below.
For examples and ready-made applications, please contact K-Patents.
9.1 Communication protocol
The communications protocol is based on UDP/IP to port 50023. It is a client/server
protocol, where the sensor is the server and thus only sends information when the
client (i.e. your computer) requests it. The server should answer to all requests within
100 ms.
9.1.1 Request format
The client to server communication, i.e. the requests sent from your computer to the
refractometer, is in binary format. The request packets contain the following binary
data (all integers are in the network order, MSB first):
−
32-bit integer: packet number
−
32-bit integer: request ID
−
(any): request data (depends on the request)
−
(any): fill-in data
Important: The maximum size of the message is 1472 octets (bytes).
The packet number is echoed back by the refractometer, but not processed in any way.
The packet numbers do not have to be sequential, any 32-bit value is valid.
The request ID is a 32-bit value that identifies the requested function, for example
refractometerinformation. See Section 9.2 for request IDs.
The request data consists of 0 to 1464 octets of additional data associated with the
request.
The fill-in data can be used to increase the number of octets in a message. Any number
of NULL characters (0x00) may be added to the end of the request as long as the total