适用于plc的工程应用人员
3.3Buffermemories
(BFM)
1)BFM#0Countermode(K0toK11),BFM#1DOWN/UPcommand
ThecountermodeisselectedfromthePLC.Asshownbelow,valuesbetweenK0andK11arewrittentobuffermemoryBFM#0formthePLC.WhenavalueiswrittentoBFM#0thecontentsofBFM#1toBFM#31areresettoWhensettingthisvalueusea(pulsed)useM9002(initialpulse)todrivetheinstruction.
Acontinuouscommandisnotallowed.
A32-bitbinarycounterwhichexecutesUP/DOWNcountingwillchangefromthelowerlimittotheupperlimitortheupperlimittothelowerlimitwhenoverflowoccurs.Boththeupperandlowerlimitsarefixedvalues:theupperlimitis+2,147,483,647,andthelowerlimitis-2,147,483,648.b)16-bitcountermodes
A16-bitbinarycounterhandlesonlypositivevaluesfrom0to65,535.Changestozerofromtheupperlimitortotheupperlimitfromzerowhenoverflowoccurs;theupperlimitisdeterminedbyBFMs#3and#2.c)1-phasecounter(K8to
K11)
d)2-phasecounter(K6,K7)
firstandcountere)