EndOfTravelLimitSetup Parameter

This table shows the value of the configuration for the parameter setting.

Table: Parameter Settings, Configurations, and Values

This setting specifies the active polarity of the Home input.

Active Low is the default. The software reports the limit input as active when the input level is low. When no external device is connected, the circuit for the limit inputs inside an Aerotech drive supplies a signal level of high to the internal logic. Thus if you use this configuration when you do not have a limit switch connected, the controller does not report the home switch as active.

When you select Active High, the software reports the home input as active when the input level is high.

Aerotech recommends that you use a normally-closed limit switch and select Active High for this setting. If you connect a normally-closed limit switch between the limit input and limit common and the switch is not activated, it stays closed and the limit inputs are pulled low by the limit switch. When the switch is activated, it opens and the limit input is pulled high by the circuit inside the drive.

The diagram that follows shows the possible wiring configurations for normally-open and normally-closed switches and the parameter setting to use for each configuration.

End of Travel Limit Input Connections

HARDWARE: This diagram applies only to drives that have end-of-travel limit inputs. To see if your drive has these inputs, refer to the hardware manual.

This setting specifies the active polarity of the negative or CCW end-of-travel limit input.

Active Low is the default. The software reports the limit input as active when the input level is low. When no external device is connected, the circuit for the limit inputs inside an Aerotech drive supplies a signal level of high to the internal logic. Thus, you can use this setting to prevent accidental limit faults when you do not have a limit switch connected. But this configuration is not fail-safe and is not recommended.

When you select Active High, the software reports the home input as active when the input level is high.

Aerotech recommends that you use a normally-closed limit switch and select Active High for this setting. This configuration supplies fail-safe limit behavior because the controller generates a fault if the external hardware is not connected or is not operating correctly. If you connect a normally-closed limit switch between the limit input and limit common and the switch is not activated, it stays closed and the limit inputs are pulled low by the limit switch. When the switch is activated, it opens and the limit input is pulled high by the circuit inside the drive.

The diagram that follows shows the possible wiring configurations for normally-open and normally-closed switches and the parameter setting to use for each configuration.

End of Travel Limit Input Connections

HARDWARE: This diagram applies only to drives that have end-of-travel limit inputs. To see if your drive has these inputs, refer to the hardware manual.

This setting specifies the active polarity of the positive or CW end-of-travel limit input.

Active Low is the default. The software reports the limit input as active when the input level is low. When no external device is connected, the circuit for the limit inputs inside an Aerotech drive supplies a signal level of high to the internal logic. Thus, you can use this setting to prevent unnecessary limit faults when you do not have a limit switch connected. But this configuration is not fail-safe and is not recommended.

When you select Active High, the software reports the home input as active when the input level is high.

Aerotech recommends that you use a normally-closed limit switch and select Active High for this setting. This configuration supplies fail-safe limit behavior because the controller generates a fault if the external hardware is not connected or is not operating correctly. If you connect a normally-closed limit switch between the limit input and limit common and the switch is not activated, it stays closed and the limit inputs are pulled low by the limit switch. When the switch is activated, it opens and the limit input is pulled high by the circuit inside the drive.

The diagram that follows shows the possible wiring configurations for normally-open and normally-closed switches and the parameter setting to use for each configuration.

End of Travel Limit Input Connections

HARDWARE: This diagram applies only to drives that have end-of-travel limit inputs. To see if your drive has these inputs, refer to the hardware manual.

This setting enables the integrated limit signals from a Heidenhain LIF481 encoder.

Disabled is the default. The limit inputs on the feedback connector are treated normally.

When you select Enabled, the limit inputs on the feedback connector correspond to the signals from the LIF481 encoder. The end-of-travel limit state is encoded into the CW and CCW hardware inputs:

• When the CCW input is high and the CW input is low, the software reports the CW end-of-travel limit as active.
• When the CCW and CW inputs are high, the software reports the CCW end-of-travel limit as active.
• When the CCW limit is low, the software reports the CW and CCW end-of-travel limits as not active. The state of the CW input does not have an effect on this report.

This setting specifies a software reversal of the end-of-travel limit inputs.

Maintain CW and CCW Switches is the default. The limit inputs are configured normally.

When you select Swap CW and CCW Switches, the CW hardware input maps to the negative or CCW end-of-travel limit and the CCW hardware input maps to the positive or CW end-of-travel limit from a software perspective.

This option specifies the configuration for opto-isolated limit inputs.

Standard Limits is the default. The end-of-travel and home limits are read from the standard encoder input connector.

When you select Opto-Isolated Limits, the end-of-travel and home limits are read from the opto-isolated digital inputs as the table that follows shows.

Table: Opto-Isolated End-of-Travel and Home Limit Inputs

Before you use the Home Limit setting, you must set the parameters that follow:

• For the HomeSetup Parameter, set Limit Type to Use Home Limit Switch.
• For the HomeType Parameter, select a setting that uses the limit.

This setting specifies which limit input is used as the home limit.

Use Home Input is the default. The home limit input is used as the home limit.

When you select Use CCW Input, the CCW end-of-travel limit input is used as the home limit. The axis cannot have a CCW end-of-travel limit.

When you select Use CW Input, the CW end-of-travel limit input is used as the home limit. The axis cannot have a CW end-of-travel limit.

This setting specifies how the controller detects end-of-travel limits.

Use Limit Switches is the default. The controller uses the signals from the dedicated limit switch inputs to determine when the axis reaches an end-of-travel limit.

When you select Use Current Limits, the controller compares the current command of the axis to the values of the EndOfTravelCurrentThresholdHigh Parameter and EndOfTravelCurrentThresholdLow Parameter parameter values to determine when the axis reaches an end-of-travel limit. The controller uses these current-based limits only until you home the axis. After the axis is homed, you must specify software-based limits to limit the travel of the axis. Refer to the SoftwareLimitLow Parameter and SoftwareLimitHigh Parameter parameters for more information.