PLC Programming

Appendix D: CoDeSys Libraries
Declaration example:
TOFInst : TOF ;
Example in IL:
CAL
LD
ST
TOFInst(IN := VarBOOL1, PT := T#5s)
TOFInst.Q
VarBOOL2
Example in FBD:
Example in ST:
TOFInst(IN := VarBOOL1, PT:= T#5s);
VarBOOL2 :=TOFInst.Q;
RTC
The function block Runtime Clock returns, starting at a given time, the current date and time.
RTC(EN, PDT, Q, CDT) means:
EN and PDT are input variables type TIME. Q and CDT are output variables type BOOL respectively
DATE_AND_TIME. When EN is FALSE, the output variables Q und CDT are FALSE respectively
DT#1970-01-01-00:00:00.
As soon as EN becomes TRUE, the time of PDT is set, is counted up in seconds and returned in CDT
as long as EN is TRUE (see example in the picture above). As soon as EN is reset to FALSE, CDT is
reset to the initial value DT#1970-01-01-00:00:00. Please note that the time in PDT is only set by a
rising edge.
10.17 The Util.lib library
This library contains an additional collection of various blocks which can be used for BCD conversion,
bit/byte functions, mathematical auxiliary functions, as controller, signal generators, function
manipulators and for analogue value processing.
As some of the functions and function blocks contain REAL variables, an accessory library named
UTIL_NO_REAL exists in which these POUs are excluded.
10.17.1 BCD Conversion
A byte in the BCD format contains integers between 0 and 99. Four bits are used for each decimal
place. The ten decimal place is stored in the bits 4-7. Thus the BCD format is similar to the
hexadecimal presentation, with the simple difference that only values between 0 and 99 can be stored
in a BCD byte, whereas a hexadecimal byte reaches from 0 to FF.
An example: The integer 51 should be converted to BCD format. 5 in binary is 0101, 1 in binary is
0001, which makes the BCD byte 01010001, which corresponds to the value $51=81.
CoDeSys V2.3 10-51