Minutes from GB/Penn Penn Array Interfaces Telecon 09may03 attendance: Mark Devlin, Simon Dicker, Mark Supanich (Penn) Brian Mason, John Ford, Melinda Mello (GB) -We agreed that programmable power supplies (in particular, the 3 shown in the "blue" floor-mount rack in MS's schematic) aren't needed. The 2 variable PS's for the digital electronics box can be replaced by a single power supply. The power supply for the analog electronics needs to be linear, and needs to have circuitry to insure things are turned on in the right order. We will shrink all this stuff and move it to the rack by the dewar (rack 1/orange). ACTION: John Ford will look into power supplies and power switching circuits. ACTION: Penn will look into current and voltage monitoring for all the DC lines. This could involve using the existing (or another) HP DAQ box, to be mounted in the custom enclosure. ACTION: Mark S. will add the AC power to the schematic. At a later point, Mark will ship GB the stepper motor for the pulse tube so that we can do RFI tests and make recommendations for mitigation. -The CAL diode is a 300 ohm resistor. We agreed that a more realtime-friendly solution for control of this would be to keep the CAL current coming from the HP DAQ box, but install a serial-controlled on/off switch in the line between power supply and diode. This will probably be controlled by a serial or parallel line from the rackmount pc, converted to fiber before the wrap. ACTION: John Ford will provide a serial to fiber interface that we use here. -We discussed the filterwheel. Space for this has been left in the dewar. Control can be done via boards that Penn has experience with which will fit in a 5"x3"x5" box, and the wheel motor requires ~20 V. There will also be 3 lines to be read out. -We briefly discussed the custom enclosure, whose details aren't yet clear, and agreed it would be prudent to leave a few inches extra in it. We expect we can shave at least 50% off the AMCO (166 lb) mil spec rack weight. We may be able to eliminate the 2nd (blue/floormount) rack since much has now moved back to the rack by the dewar. ACTION: John Ford will check on whether we have space for the computer (and GPIB/fiber, serial/fiber boxes) in an existing rack. -Although we have drivers for the custom fiber card (ie we should be able to send strings to it under debian linux), that interface is still a black box (ie we don't know what strings to send, or what data we'll get back); we will fix this by... ACTION (Mark Devlin): contact Randy Dorwort at NIST and obtain more documentation for the readout electronics interface; keep us posted re: results from the Princeton group's NIST trip; obtain Java DAQ software from GSFC and send it our way. Mark will also get Brian & Melinda added to the (mostly non-software related) GSFC array detector development mailing list. ACTION (Brian): independently, contact Scuba-2 and see if they have some documentation of the readout interface which could be of use. -GB would like to use RT linux under our standard supported version of red hat. We will probably get a debian driver. We left open the issue of how to get there from here.