**** Plot Descriptors ***************************************************** g t byt sb #b fm l p o e md <----------sf--------> <----prompt----> <--lower--> <--upper--> <----------------title--------------> 0 0 036 00 32 00 0 0 2 0 00 8.381903171539e-8 T-02 Lat 0.000000000 0.000000000 T-02 Latitude (deg) g = # graphs per screen: 0 = single, 1 = double, 2 = triple t = graph type: 0=1 item, 1=2i, 2=3i, 3=i vs i, 4=i-constant, 5=i-i 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 l = limts: 0 = range, 1 = auto, 2 = fixed, 3 = center, 4 = relative p = plot mode: 0 = line mode, 1 = point mode o = fixed point and floating point data byte order (below) e = exponent: 0 = decimal limit display, 1 = exponent limit display md = modifier: 0=none,1=sqrt,2=dircos->lat,3=deltas with rollover,4=deltas 5=seg,min->deg fm = format (bytes): 0=fix (1-4), 1=ufix (1-4), 2=sign/mag fix (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) sf = scale factor for item or constant for item - constant prompt = screen prompt to select item (not used in multi graph item) lower = lower graph limit for fixed offset (l=2) upper = upper graph limit for fixed offset (l=2) title = title of graph on display The last entries in a descriptor file may be multi graph items (non zero g or t). When this occurs, byt, bt and #b point to other graphs (1st entry is 0, 2nd entry is 1, etc.) and the second line (lower, upper,title) is omitted. 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 | ---------