1. Registers are always 32 bit / 4 byte memory is accessed directly when memory cannot be accessed kind of flag is on

2. Command IDBlock Nr.Nr. of Words Command Word 1 Command Word 2 … MarkerChecksum Command IDBlock Nr.Nr. of Words Command Word 1... End Marker Word SW 0 8 1624 31 HW 31 24 168 0 Protocol for RCU-specific Commands

3. Command IDBlock Nr.Nr. of Words Status Word Result Word 1 … MarkerChecksum Command IDBlock Nr.Nr. of Words Status Word Result Word... End Marker Word SW 0 8 1624 31 HW 31 24 168 0 Protocol for RCU-specific Results

4. Command ID: (8 bit) Command identifier (for details, see 7.2.1) Command identifier Safety message identifier (1 if the message is a safety message, 0 if not) Packed format bit (1 if the message contains packed 3 * 10 bit words. Used for Pedestal Data) Not used/Don’t care. Available for future use IdentifierMeaning 0001Single read 0010Single write 0011Multiple read 0100Multiple write 0101Random read 0110Random write

5. Block Nr: (8 bit) The block number reflects if there are more instructions to handle. It is decremented inbetween one collection of instructions / blocks Number of Words: (16 bit) Number (Integer) of 32 bit data words in command block. Including information word and marker word. Marker: (16 bit) Marker word id, coded as AA55 (hex). Checksum: (16 bit) Checksum, which will be compared with the checksum computed by the Configuration Module/DCS IM End Marker Word: (32 bit) End marker id, coded as DD33 (hex).

6. IdentifierMeaning 0001Single read: - address word 0010Single write: - address word - Data 0011Multiple read - address word - number of data words to read 0100Multiple write - address word - number of data words - data word 1 : - data word N 0101Random read - address word 1 - address word 2 : - address word N 0110Random write - address word 1 - data word 1 - address word 2 - data word 2 : - address word N - data word N Possible Commands: (TPC-RCU)

7. FEE Server (DIM - Server on RCU - Card) PVSS Server (DIM - Server) FEE Client (DIM - Client) InterCom Layer (Application layer) Database Access PVSS Client (DIM - Client) Communication Layers