Tow system operation

This section provides instructions on operating the tow carriage motion system. Before attempting to operate any equipment, please read these general operating guidelines and become familiar with the tow system technical details.

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CAUTION: Before considering towing, check the tow system status whether the tow system is operational, and whether there are maintenance issues that need to be addressed. Users will be held liable if tank status or maintenance issues are ignored and this results in damage.

WARNING: Before initiating motion, always check that the carriage path is free from obstructions, and that position targets are within the limits. Failure to do so could result in severe damage to the system, injury, or death.

CAUTION: The system has not been thoroughly tuned/tested at speeds above 2 m/s. Towing at higher speeds may cause an overcurrent fault. At these higher speeds, it is especially necessary to keep the path free from obstruction and avoid target positions outside the limits.

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Startup procedure

Figure 1: Power disconnects.

1. Before any operation of the tow system, be sure the carriage path is free from equipment, debris, and/or personnel.
2. Switch on the on-board servo power disconnect (3rd from the left), shown in Figure 1.
3. Wait at least 30 seconds, then switch on the tow tank controller cabinet disconnect (HP4-7,9,11 tag) located on the near side of the tank wall near the wave maker, shown in Figure 2.

Simple carriage motion: using Tow

Basic operation of the tow system can be achieved using the Tow application. Tow is a simple user interface for executing point-to-point and jog motion of the tow carriage. To get started:

1. Log on to the Tow Tank PC up on the control platform using the "User" account. There is no password.
2. Launch the Tow app by clicking the icon on the taskbar. The app will automatically attempt to connect to the controller. If the attempt is unsuccessful, make sure the controller is powered-on and the SPiiPlus User Mode Driver is running in the system tray.
3. Once connected, the main window will be shown, as in Figure 3. The axis can be enabled by clicking the "Enable" button.

Homing

Point-to-point moves in absolute coordinates are disabled until the axis has been homed, a process where the carriage moves until it contacts the negative (beach side) limit switch, then zeros its reference position. The homing routine can be called by selecting "Run Homing" from the "Homing" menu.

Point-to-point motion

Point-to-point moves can be executed in either relative or absolute coordinates. Note that moves in absolute coordinates require the axis to be homed. See section above for homing routine execution. To execute a point-to-point move, type the desired target position, velocity, and acceleration/deceleration into the corresponding boxes, then press "GO". The "Halt" button will stop motion at the specified deceleration, whereas the emergency stop buttons will stop motion at maximum deceleration.

Shortcuts

There are three shortcut buttons for executing point-to-point moves to common target positions. These shortcut buttons are not enabled until the axis has been homed. Note that the left limit shortcut is calculated based on the YZ traverse carriage offset setting. Ensure this value is correct in the Options->Traverse Offset menu. Failure to do so could result in the axis being disabled and rapidly decelerated due to contact with the left limit switch.

Jog motion

The axis can be jogged at low speed directly from the application via the left and right-arrow buttons on the main toolbar. The jog pendant, located on the carriage, can be activated/deactivated by pressing the "Pendant" button. Note: a quick double-press of a jog button will latch the jog motion. It can be unlatched by pressing either jog button.

Shutdown procedure

1. Close the Tow (or SPiiPlus) application and log-off or lock the Tow Tank PC (do not shut down).
2. Turn off the controller cabinet disconnect (HP4-7,9,11 tag) shown in Figure 2.
3. Turn off the on-board servo disconnect, shown in Figure 1.

Advanced operation

This section details methods for operating the tow system beyond the capabilities of Tow.

SPiiPlus MMI Application Studio

SPiiPlus MMI Application Studio is provided by ACS, the controller manufacturer. The software allows development and execution of ACSPL+ motion programs stored in the controller's memory buffers, as well as sending individual commands to the controller via terminal. Sample code, taken from the program stored in buffer 4, which executes a single point-to-point move, is shown below:

ACC(tow) = 0.5    ! Sets the tow axis acceleration to 0.5 m/s^2
DEC(tow) = 0.5    ! Sets the tow axis deceleration to 0.5 m/s^2
VEL(tow) = 0.5    ! Sets the tow axis velocity to 0.5 m/s
JERK(tow) = 10    ! Sets the tow axis jerk to 10 m/s^3
target = 10.2     ! Sets target position variable to 10.2 m

ptp/e tow, target ! Point-to-point move on tow axis to 'target'

STOP

See ACSPL+ programs for descriptions of programs already in the controller, and more sample ACSPL+ code.

Terminal commands

Below are some examples of commands that can be sent to the controller via the terminal. For a full list of commands see the ACS documentation.

Point-to-point move on the tow axis to absolute position 8 m. The "e" modifier tells the controller to wait until any motion in progress is complete before executing another command:

ptp/e tow, 8

Point-to-point move relative 1 m towards the beach:

ptp/r tow, -1

Disable and enable the tow axis, respectively:

DISABLE(tow)

ENABLE(tow)

Halt motion on the tow axis:

HALT(tow)

Kill motion on the tow axis, similar to pushing an emergency stop, the axis decelerates at the maximum allowable deceleration:

KILL(tow)

Print the tow axis reference position:

?RPOS(tow)

In general, a question mark preceding any variable name will query the controller for the variable's current value.

Start the program in buffer 2 in the controller from line 1:

START 2, 1

ACS C library

The ACS controller includes a C library for developing user applications. ACSpy is a Python package that wraps this library for fast development of motion applications.

ACS COM library

The ACS controller includes a COM (ActiveX) library for developing user applications in various languages, e.g. LabVIEW.