**** Print Descriptors **************************************************** <---------sf-------->|byt|bt|#b|o|md|ft|<-format|header1|header2-->| 1.0000000000000000000|004|15|01|0|00|01| %8.4lf | X vel | (f/s) | |<-variable length fields-->| byt = starting byte (see below) bt = starting bit (fixed pt only) : lsb = bit 0, msb = 31 (max) #b = number of bits (fixed pt only): 1 to 32 (max); bt + #b < 32 o = fixed point and floating point data byte order (below) md = modifier: 0=none,1=sqrt,2=dircos->lat,3=deltas with rollover,4=deltas fm = format (bytes): 0=fix(1-4), 1=ufix(1-4), 2=int(1-4), 3=uns(1-4), 10=EEEs (4), 11=EEEd (8), 12=DECs (4), 13=DECd (8), 14=MILs (4), 15=MILd (6), 16=C30s (4), 17=C30d (8), 18=CAPs (4), 19=CAPd (6) For format types (0,1,10-19) use double specification (e.g. %lf) For format types (2,3) use long specification (e.g. %ld,%lu) The "number of bits + start bit" determines how many bytes are used to form fixed point data: < 9, 1 byte The number of bytes used must be considered < 17, 2 bytes in determining byte order (below). < 25, 3 bytes The number of bytes used to form floating else, 4 bytes point data is predetermined. **** Byte ordering ******************************************************** byte order | v 1 2 3 4 6 8 <-- number of bytes 0 a ab abc abcd abcdef abcd efgh correct PC order (ls byte first) 1 a ba cba dcba fedcba hgfe dcba bytes are in reverse order 2 a cdab efcdab cdab ghef word reverse 3 a badc badcfe badc fehg byte in word reverse 4 a efgh abcd double word reverse 5 a dcba hgfe word reverse, byte in word reverse 6 a fehg badc double word rev, byte in word rev 7 a ghef cdab double word reverse, word reverse **** Byte offsets into messages ******************************************* NORMAL MESSAGES byte 1 RTtoBC 2 BCtoRT 3 RTtoRT 4 MCw/o 5 MCxmt 6 MCrec ---- --------- --------- --------- --------- --------- --------- -02 | TCW | | RCW | | RCW | | TMC | | TMC | | RMC | --------- --------- --------- --------- --------- --------- 00 | LBW | | DW1 | | TCW | | LBW | | LBW | | DW1 | --------- --------- --------- --------- --------- --------- 02 | MSW | | DW2 | | LBW | | MSW | | MSW | | LBW | --------- --------- --------- --------- --------- --------- 04 | DW1 | | DW3 | | MSW | | DW1 | | MSW | --------- --------- --------- --------- --------- 06 | DW2 | | DW4 | | DW1 | where: --------- --------- --------- : : : : : : TCW = transmit command word --------- --------- --------- RCW = receive command word 2n-2 | DWn-2 | | DWn | | DWn-3 | TMC = tramsmit mode code --------- --------- --------- RCW = receive mode code 2n | DWn-1 | | LBW | | DWn-2 | RBC = receive broadcast --------- --------- --------- TBM = transmit broadcast mode 2n+2 | DWN | | MSW | | DWn-1 | RBM = receive broadcast mode --------- --------- --------- MSW = mux sataus word 2n+4 | DWn | DW = data word --------- LBW = loop back word 2n+6 | MSW | --------- BROADCAST MESSAGES byte 7 BCtoRTs 8 RTtoRTs 9 MCw/o 10 MCrec ---- --------- --------- --------- --------- -02 | RBC | | RBC | | TBM | | RBC | --------- --------- --------- --------- 00 | DW1 | | TCW | | LBW | | DW1 | --------- --------- --------- --------- 02 | DW2 | | LBW | | LBW | --------- --------- --------- 04 | DW3 | | MSW | Note: --------- --------- 06 | DW4 | | DW1 | The 1553 interface card deposits 16 --------- --------- bit data into memory in the correct : : : : PC order, lsbs 1st (even byte). --------- --------- 2n-2 | DWn | | DWn-3 | UUT 32 bit data is deposited MSH then --------- --------- LSH, which is PC word backward. The 2n | LBW | | DWn-2 | data reduction routines swap the --------- --------- 2 words for items > 16 bits. 2n+2 | DWn-1 | --------- 2n+4 | DWn | ---------