Delta RMC101 User Manual
Page 914
RMC100 and RMCWin User Manual
E-24
Step 13 immediately links back to step 11 to restart the polling loop. Notice that this extra step
does take one control loop to process and therefore increases the time taken to process the
entire polling loop by one control loop (1 or 2 ms).
Step 14 handles the timeout condition by turning on discrete output 0.
Now, compare this method of implementing a timeout with the one used in the next example,
which is a little more difficult to follow but removes the need for the extra do-nothing step in the
polling loop (step 13 above).
Example 3:
This example offers an alternative approach to the same problem as Example 2: the user wants
to make a move and wait for the move to complete or a timeout to occur. It is a little more difficult
to follow, but removes one step from the polling loop, therefore reducing the amount of time taken
to catch any condition. Keep in mind that for many applications, this slight gain in performance
will not justify the reduction in clarity.
Step 10
Step
11
Step 12
Step 13
&
Mode
0x0081
0x0081
0x0081
0x0000
Accel
100
100
100
0
Decel
100
100
100
0
Speed
10000
10000
10000
0
Command
Value
4000
0
0
0x0001
Command
G
?
?
[
Commanded
Axes
Default
Default
Default
Default
Link Type
TimerSt/Exp
BitsON
TimerNExp
DelayMS
Link Value
0
0x0001
5000
0
Link Next
11
14
11
14
Step 10 initiates the move to 4000, starts the timer, and links immediately to step 11.
Step 11 checks the In Position bit of the Status Word using the BitsON (b) link type. Therefore, if
the axis is in position, then the link is taken to step 14. Otherwise, control passes to step 12.
Step 12 checks if 5000 ms (five seconds) have expired since the timer was started in step 10.
Notice that, this time, the Timer Not Expired (t) link type is used. Therefore, if the timeout has not
occurred, then control jumps back to step 11. If the timeout has occurred, then control passes to
step 13.
Step 13 handles the timeout condition by turning on discrete output 0.
Here is a summary of the advantages and disadvantages of doing a polled loop using this method
versus the method shown in Example 2:
• The advantage of this method is that the timeout and the In Position bit will be checked every two
control loops since there are only two steps in the polling loop (steps 11 and 12).