Chapter 3 Connecting Hardware
Overview
The DMC-40x0 provides opto-isolated digital inputs for forward limit, reverse limit, home, and abort signals.
The controller also has 8 opto-isolated, uncommitted inputs (for general use) as well as 8 high power opto-
isolated outputs and 8 analog inputs configured for voltages between +/- 10 volts.
Controllers with 5 or more axes have an additional 8 opto-isolated inputs and an additional 8 high
power opto-isolated outputs.
This chapter describes the inputs and outputs and their proper connection.
Using Optoisolated Inputs
Limit Switch Input
The forward limit switch (FLSx) inhibits motion in the forward direction immediately upon activation of the switch.
The reverse limit switch (RLSx) inhibits motion in the reverse direction immediately upon activation of the switch.
If a limit switch is activated during motion, the controller will make a decelerated stop using the deceleration rate
previously set with the SD command. The motor will remain on (in a servo state) after the limit switch has been
activated and will hold motor position.
When a forward or reverse limit switch is activated, the current application program that is running in thread zero
will be interrupted and the controller will automatically jump to the #LIMSWI subroutine if one exists. This is a
subroutine which the user can include in any motion control program and is useful for executing specific instructions
upon activation of a limit switch. Automatic Subroutines for Monitoring Conditions are discussed in Chapter 7
Application Programming.
After a limit switch has been activated, further motion in the direction of the limit switch will not be possible until
the logic state of the switch returns back to an inactive state. This usually involves physically opening the tripped
switch. Any attempt at further motion before the logic state has been reset will result in the following error: “022 -
Begin not possible due to limit switch” error.
The operands, _LFx and _LRx, contain the state of the forward and reverse limit switches, respectively (x represents
the axis, X, Y, Z, W etc.). The value of the operand is either a ‘0’ or ‘1’ corresponding to the logic state of the limit
switch. Using a terminal program, the state of a limit switch can be printed to the screen with the command,
MG_LFx or MG_LRx. This prints the value of the limit switch operands for the ‘x’ axis. The logic state of the
limit switches can also be interrogated with the TS command. For more details on TS see the Command Reference.
DMC-40x0 User Manual Chapter 3 Connecting Hardware • 32
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