Chapter 3 Connecting Hardware
Overview
The DMC-40x0 provides optoisolated digital inputs for forward limit, reverse limit, home, and abort signals. The
controller also has 8 optoisolated, uncommitted inputs (for general use) as well as 8 high power optoisolated
outputs and 8 analog inputs configured for voltages between ±10 volts.
Controllers with 5 or more axes have an additional 8 optoisolated inputs and an additional 8 high
power optoisolated outputs.
This chapter describes the inputs and outputs and their proper connection.
Overview of 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. The controller can be configured to disable the axis upon the activation of a
limit switch, see the OE command in the command reference for further detail.
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. Any attempt at further motion before the logic state
has been reset will result in the following error: “22 - 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, A, B, C, D 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.
Chapter 3 Connecting Hardware ▫ 33 DMC-40x0 User Manual
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