Marc Lacasse and Rafael Millan-Gabet,  June 2000
mlacasse@cfa.harvard.edu, rmillan@cfa.harvard.edu

Here are the steps to operate the long delay with the server-client software.


Server: Linux PC in the hut at the end of long arm. This machine controls the motion and records the position of the Long Delay carriage, which carries the dihedral mirror.

Client: Apple Quadra in control room. Provides user interface inside the control room.

The Long Delay motor (to move the Long Delay carriage) and laser interferometer (to measure its position) are also in hut at end of long arm.


This set of instructions can also be found in the Desktop of the Delay Line Control Quadra. A summary of the steps needed to start the server software will also appear in the terminal window as soon as you log in the Linux server.

0) Turn on power to LD motor and laser. Laser needs a few minutes to warm up before it reports accurate positions. In order for the laser to correctly report the Long Delay Line position over its full range (approx. 2900 cm), it needs to be properly aligned. This document assumes this is the case, and instructions to make this adjustment should be found elsewhere.

1) Use a free terminal in the control room to telnet to the ldelay linux box (IP address:

2) Log in as:

        obtain username and password from Marc Lacasse

you will get a greeting message, with instructions on how to start the server software, repeated below.

3) Type the following to become root:

        su -

        obtain root password from Marc Lacasse

4) First load the at6400 module and the HP885 module by typing:


5) Load the UDP server software by typing:


6) Start the client software in the IOTA Delay Line Control Quadra (currently DelayLine2.0.3).  This usually needs to be started twice. (See notes below)

7) Use the Quadra software (currently DelayLine2.0.3) Long Delay Menu to Home, Index, and/or Move the Long Delay the desired distance (use the Move Servo option).

Distances along the Long Delay Line start at 0 cm and go out approx. +2900 cm.

Remember to correct the Long Delay dihedral yaw angle after every long delay line move. Instructions elsewhere.

8) At the end of the night, turn off the power to the LD motor and laser (out in the hut). Those two are plugged into a single power strip that just needs to be turned off. Do not turn off anything else, particularly the Linux box.

Notes: =====

If the motor or laser is turned off or if the laser loses lock, you need to Quit the server (Linux) software, by typing CTRL C in the Linux telnet window, and re-run the ./srv1 and ./srv2 scripts.

If the delay hits the p-cut switch you should remove the connection on the screw block which is labeled p-cut and put in a pull down resistor to the adjacent ground.

When properly running you will get a Command Error message when the client (Quadra) software starts, and then a Axis 2 Fault message (we do not use the second long delay line yet).  The fact that the Command Error message is *needed* is a bug as yet not fixed. If you do not get this error message, you need to QUIT and Restart the client (Quadra) software.  If you also get an Axis 1 error message check the power to the motor amplifier.

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