Galil DMC-3425 user manual Overview, Using Inputs, Limit Switch Input

Chapter 3 Connecting Hardware

Overview

The DMC-3425 provides digital inputs for A and B forward limit, A and B reverse limit, A and B home input and abort input. The controller also has 3 uncommitted, TTL inputs, 3 TTL outputs and 2 analog inputs (12-bit).

The DMC-3415 provides a forward and reverse limit, home input and abort input. The controller also has 7 uncommitted, TTL inputs, 3 TTL outputs and 2 analog inputs (12-bit).

This chapter describes the inputs and outputs and their proper connection.

Using 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 DC command. The motor will remain on (in a servo state) after the limit switch has been activated and will hold motor position. To set the activation state of the limit switches refer to the command CN, configure, in the Command Reference.

When a forward or reverse limit switch is activated, the current application program that is running will be interrupted and the controller will automatically jump to the #LIMSWI subroutine if one exists. This is a subroutine that the user can include in any motion control program and is useful for executing specific instructions upon activation of a limit switch.

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, return the state of the forward and reverse limit switches, respectively (x represents the axis, A or B). The value of the operand is either a ‘0’ or ‘1’ corresponding to the logic state of the limit switch, active or inactive, respectively. If the limit switches are configured for active low, no connection or a 5V input will be read as a ‘0’, while grounding the switch will return a ‘1’. If the limit switches are configured for active high, the reading will be inverted and no connection or a 5V input will be read as a ‘1’, while grounding the switch will return a ‘0’.

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

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