accelerator control system (1)

Now that we’re moving on the electronic rebuilding phase. Here’s a short description of how the accelerator control system will actually work.

terminal elec–FO-|…………………………………………|—-USB input
……………………………|-FO–analog control panel–|
source elec—FO-|…………………………………………|—-USB output

Within both the source and terminal electronics boxes, analog voltage control (input) and analog voltage monitoring (output) interface with the fiber optics (FO) boxes and are converted to digital FO signals. The signals are converted back to analog at the control panel. To interface with the control panel, we will be getting two USB devices: one 8-channel input (plus 2 output channels) and one 16 channel output. Both units come with enough binary digital I/O channels to choke a horse. The fiber optics portion of the system should be transparent to us, provided it functions as ordered.

This system has some useful features.

• It incorporates full feedback for every controlled parameter. As obvious as this seems to me, there are a lot of fancy-pants scientific equipment that misses this, and thus can’t make basic determinations as to whether or not their equipment is functional.
  “What is the voltage output to the y-steerer?”
  “Uh, I turned the control knob up to 11, so I guess 11.”
  “Is the beam being steered?”
  “Uh, doesn’t look like it.”
  “So is something wrong?”
  “Uh, probably.”
• Since we have feedback, we have the option of closing the feedback loops with controllers in the future. Process control can be tricky, so starting out your system with closed feedback control on everything leads to a lot of fighting control systems and less actual running the accelerator, so we have the option to do it later but we don’t have to do it now.
• The control system has a natural analog breakout point at the control panel. If something isn’t responding correctly from the computer, you can stick a voltmeter in the control panel and see if you’ve got the correct signal going through, rather than trying to figure out if the baud rate on your RS232 device interface is set correctly or is your port forwarding settings mesh with the new TCP/IP management software the department installed.