4-160 Series 90-30/20/Micro Programmable Controllers Reference Manual – September 1998 GFK-0467K
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SVCREQ #16: Read Elapsed Time Clock Use the SVCREQ function with function number 16 in order to read the value of the system’s
elapsed time clock. This clock tracks elapsed time in seconds since the PLC powered on. The
timer will roll over approximately once every 100 years.
This function has an output parameter block only. The parameter block has a length of 3 words.
seconds from power on (low order) address
seconds from power on (high order) address + 1
100 microsecond ticks address + 2
The first two words are the elapsed time in seconds. The last word is the number of 100
microsecond ticks in the current second.
Example:
In the following example, when internal coil %M0233 is on, the value of the elapsed time clock is
read and coil %M0234 is set. When it is off, the value is read again. The difference between the
values is then calculated, and the result is stored in register memory at location %R0250.
The parameter block for the first read is at %R0127; for the second read, at %R0131. The
calculation ignores the number of hundred microsecond ticks and the fact that the DINT type is
actually a signed value. The calculation is correct until the time since power-on reaches
approximately 50 years.
| _____
|%M0233 | | %M0234
|——| |———| SVC_|———————————————————————————————————————————————————————————(S)—
| | |
| | REQ |
| | |
| CONST —|FNC |
| 00016 | |
| | |
|%R0127 —|PARM |
| |_____|
|
| _____ _____
|%M0233 %M0234 | | | | %M0234
|——|/|———————| |———| SVC_|——————————————————| SUB_|————————————————————————(R)—
| | | | |
| | REQ | | DINT|
| | | | |
| CONST —|FNC | %R0131 —|I1 Q|— %R0250
| 00016 | | | |
| | | | |
| %R0131 —|PARM | %R0127 —|I2 |
| |_____| |_____|
|