88 User Manual Synertia® RF Generator
The information contained in this manual is subject to change by Comet Yxlon without prior notice.
10 Host Port communication
10.1 Host Port communication via SHFT
protocol
10.1.1 Understanding the SHFT protocol
The Synertia® RF generators use Comet's SHFT protocol for digital host port
communication. The protocol is based on the Modbus/RTU protocol and implements a
point-to-point communication between the host, which could be for example a PLC or a
computer, and the generator.
Even though the SHFT protocol is based on the Modbus/RTU protocol, it only supports
two non-standard function codes (FC) – 0x41 for reading and 0x42 for writing data.
Other common Modbus function codes are not supported.
The SHFT protocol uses pure binary data. Transfer of data in ASCII format is not
supported.
The general structure of the protocol is independent from the underlying communication
interface, which can be RS-232, Ethernet or any other available fieldbus. However, there
are some specifics due to different handling of data on the employed interface. This
chapter explains the general principle of the SHFT protocol, whereas the specifics for the
different interfaces are explained in the succeeding chapters.
10.1.2 SHFT protocol – Request
Every transaction consists of a request from the host and the corresponding response
from the generator. The host initializes the communication by sending a request to the
generator. Depending on the amount of transferred data, the request can have a length
between 5 and 253 bytes. It consists of header, command number and data. The following
table shows the structure of the request.
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