Owner's manual
V440UserMa
7430‐0131‐01Rev.F
Page59
NA nual
Chapter8. ProgrammingGuide
ThissectionofthemanualassumesthattheuserisfamiliarwithANSICprogramminglanguageanddataNOTE:
typeconventions.
The440Seriessupportacommonpacketstructurethatincludesbothcommandorinputdatapackets,and
measurementoutputorresponsepacketformats.Thissectionofthemanualexplainsthesepacketformatsaswell
asthesupportedcommands.NAV‐VIEW2.2alsofeaturesanumberoftoolstounderstandthepackettypes
availableandtheinformationcontainedwithinthepackets.Foranexampleofthecoderequiredtoparseinputdata
packets,referto
AppendixC.SamplePacket—ParserCode.
GeneralSettings
TheserialportsettingsareRS232with1startbit,8databits,noparitybit,1stopbit,andnoflowcontrol.Thebaud
00,38400,and57600.
ratessupportedare9600,192
Common
definitionsinclude:
•
Awordisdefinedas2bytes,whichare16bits.
• Allcommunicationstoandfromtheunitarepacketsthatstartwithasinglewordalternatingbitpreamble
0x5555.ThisistheASCIIstring“UU”.
•
AllmultiplebytevaluesaretransmittedBigEndian(MostSignificantByteFirst).
• AllcommunicationpacketsendwithasinglewordCRC(2bytes).CRC’sarecalculatedonallpacketbytes
excludingthepreambleandCRCitself.InputpacketswithincorrectCRC’swillbeignored.
• Eachcompletecommunicationpacketmustbetransmittedtothe440Seriesinertialsystemwithinafour
(4)secondperiod.
NumberFormats
NumberFormatConventionsinclude:
•
0xasaprefixtohexadecimalvalues
•
Singlequotes(‘’)todelimitASCIIcharacters
• Noprefixordelimiterstospecifydecimalvalues
Thefollowingtabledefinesnumberformats:
Table11NumberFormats
Descriptor Description Size(bytes) Comment Range
U1 UnsignedChar 1 — 0to255
U2 UnsignedShort 2 — 0to65535
U4 UnsignedInt 4 — 0to2^32‐1
I2 SignedShort 2 2’sComplement ‐2^15to2^15‐1
I2* SignedShort 2 Shifted2’sComplement Shiftedtospecifiedrange
I4 SignedInt 4 2’sComplement ‐2^31to2^31‐1