AMS DCB-274 manual Wait, Lower case W Pre-energize

ADVANCED MICRO SYSTEMS, INC.					SMC-27X2 SOFTWARE
Command	Function		Type			NV Bytes
W	Wait (n) Milliseconds		Immediate, Program			3
	Mnemonic	Data 1		Data 2		Result
	(Name) W (n)	10 ms. (0-65,535)		None		None

W (Wait)

The controller will remain in an idle state for the specified time. The Wait command, if issued while indexing (as a result of an R, +, -, or F command), timing will NOT start until the motion has completed.

Wait until motion complete

Using this command with zero time can provide an alternate method of determining motion. If issued while running at constant velocity, the time -out will occur without waiting for motion to cease. High-speed step operation during Wait commands will increase the delay time by as much as 14 times the normal value. The result will NOT be available until the delay is complete.

The following example program makes a move, waits for motion to complete, then turns on an output port. Some uses for this could be illuminating a LED, signaling a sequence is complete or operating a valve.

P 0 Enter program mode.

+1000 Move 1000 steps in the plus direction.

W 0 Wait for move to finish.

A 8 Turn on port 4.

W 500 Wait 50milliseconds.

A 0 Turn off port.

P 0	Exit program mode.
Command	Function		Type		NV Bytes
w	Wait (n) Milliseconds		Immediate, Program		3
	Mnemonic	Data 1		Data 2	Result
	(Name) w (n)	10 ms. (0-255)		None	None

w (lower case W; Pre-energize)

The “w” command is a “pre-energize” command that can insure that motor current has built up when a step command is executed while in the “holding current” state. This parameter is useful under certain conditions, and should be zero (off) if possible. The following conditions might require “pre -energize” time:

1.Automatic current setback (“E” command) is in effect.

2.If the delay between consecutive motion commands exceeds 1 second.

3.If the initial speed (“I” command) specified is too high.

4.If the acceleration requirements are excessive.

When the auto current setback is used, motor current will be reduced after approximately one second of idle time. When a new motion command (+, -, R, M, F, etc) is executed the windings are re-energized almost instantly with the first motor step. Thus the motor must rapidly change from a “relaxed” position to the next step.

This pre-energize insures a delay after turn on. The delay is not used if the setback timeout (from a prior motion) is not timed-out. That is, the motor current is still at 100%. The drawback is that this function can introduce a substantial start delay.

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