DS200SDCCG1AFD gas turbine electric card

  The function code determines the interpretation of the address/ control field. The function codes are categorized as depicted in Table 61 below. The individual functions, and the contents and interpretation of the address/control field, are described in the subsections below. Function codes not indicated in Table 61 are currently unused.All frames are encoded according to the Manchester II Bi-phase L Coding standard and protected by CRC protection bytes providing excellent security. The generator polynomial is: extended with an overall even parity bit. In order to build the protection byte, all eight bits computed are inverted.The master and slave preambles are two different bit patterns which both violate the Manchester II coding rules. They therefore pose a high security against wrong synchronization of the frames.

Process Data Transfer

 Process data transfer is implemented through the concept of signal addresses. The signal address is a logical address uniquely identifying the sender of a certain process data value, corresponding to a sending DSP. The signal addresses are assigned automatically by the Advant Station 100 Series Engineering Station from the IDENT and STATION attributes of the DSPs. The concept of signal addresses has thus been hidden from the user. When process data transfer is attempted, the address/control field of the master frame contains the signal address identifying the process data value. The communication interface which is source for the signal address in question (that is the communication interface where the corresponding sending CDP is configured) responds with the slave frame proper (see Figure 110), containing the current data of the CDP

The signal address also acts as a filtering mechanism. 

Each communication interface may define a table of signal addresses which it would like to receive. This facility is employed by the communication interface to ignore all signal addresses but those for which a receiving DSP has been defined. The size of the slave frame depends on the function code. The correlation appears from Table 62 below.