Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 663)

Paramacros
Chapter 20
20-19
For example, programming:
#3000=.1 (WHEEL NUMBER 6 IS WORN);
causes program execution to stop at the beginning of this block and display
a message telling the operator to read the comment in the block. A block
reset must be performed before a cycle start can resume normal program
execution.
When this block is executed, it also sets the paramacro alarm PAL flag
($MCALRM) true. See your system installer’s documentation for details
on the effect of this PAL flag.
#3001
System Timer (PAL)
Use this parameter to enter or monitor the system timer value. It is a
read-write parameter. Every 20ms a value of 20 is added to the value of
this parameter.
The value of this parameter is stored in a PAL flag ($PM20MS) and can be
modified or set by your PAL program. See the documentation prepared by
your system installer for details on the use of this timer. The maximum
value of this parameter is 32768ms. Any value greater than 32768 causes
this parameter to “rollover” to zero and restart counting. The value of this
parameter is reset to zero every time power is lost.
#3002
System Clock
Use this parameter to enter or monitor the system clock value. The system
clock parameter references an internal hour counter. It is a read-write
parameter.
The maximum value for this parameter is 1 year (8760 hours). The value
is maintained when power is lost. It is incremented by .000005556 every
20ms. Negative value assignments are illegal.
#3003
Block Execution Control 1
Use this parameter to determine whether the control ignores single block
mode and to determine when M-codes are executed in a block. The value
of this parameter ranges from 0 to 3. It is a write-only parameter.