MDM Observatory's 8K CCD array project based at Columbia Astrophysics Laboratory: RE-ESTABLISHING 8K/COMPUTER FIBER COMMUNICATIONS
Arlin Crotts e-mail: (
Telephone: (212) 854-7899

CAUTION: do not strain the fiber cables, either by pulling on their ends, by bending them radically, or by crushing them with heavy objects. In some instances, lengths of fiber cable may even stretch across the floor; be especially careful not to crush these.

Hit <return> at the DetCom prompt. Any time you hit <return>, the program will attempt to communicate with the controllers. If the fiber optic link cables are properly connected, you will get a green message indicating communications are OK.

If you persist in getting a red error message after a <return> at the detcom prompt, either communications across the fiber optic links are faulty, or the controllers need to be reset. To troubleshoot the situation, proceed as follows:

Look behind the host computer and if both fibers are correctly connected to each interface card (at the back of the computer) then one should see a green light below the fiber connectors. If you don't see one (or both) of the green lights, be sure the fibers are connected at the CCD controller box end, then return to the computer. At the computer, you may need to reset the interface cards using the pushbutton on each card---choose the appropriate one: master or slave. If you still are missing a light, swap the fibers at that interface card. If the light still does not come on, there is potential fiber damage. If both green lights are on, but you still get a red error message at the <return>, then reset the appropriate (MASTER or SLAVE) grey controller power supply box by hitting its black reset push button.

If you cannot see the back of the computer for some reason, do the following: Hit <return> at the detcom prompt. After hitting <return>, one of the following cases will occur:

If you get red messages complaining that there is no communication for either MASTER or SLAVE, then the fiber pair is probably backwards - try swapping the two fibers at the MASTER.

If you get a message in green saying the computer can communicate with the MASTER, but not the SLAVE, then all is OK. You have now verified that the MASTER is indeed connected to the proper S-bus interface.

If you get a message saying the computer can communicate with the SLAVE, and not the MASTER, then you have the fiber cables mixed up between the MASTER and SLAVE - the cables are actually connected to the MASTER, but the computer thinks it is taking to the SLAVE. Swap the fiber cables BETWEEN the boxes - you can do this at the computer end or the telescope end, whatever is more convenient.

Once you have the cables connected properly to the MASTER and have the MASTER talking to the proper interface, then connect the SLAVE fiber cables and turn on the SLAVE power supply.

Again, hit RETURN at the Detcom prompt and one of the following will occur:

You will successfully communicate to the MASTER, but not the SLAVE. This is probably due to the SLAVE fibes being backwards. Swap the two fiber cables at the SLAVE box. You will get a green message indicating communications are OK.

Finally, you might want to check that the small fiber optic link between the two electronic boxes is properly connected (into the side of the boxes opposite the high-voltage status LEDs).

You can now continue with setting up the instrument.