Installing the Mode Cleaner
The mode cleener board installation required a combination of EPICS, VME, statecode and electronica that isn't found in any one place. This page will document the adventures of David and Jenne, Sam and Bob as they travel through MC installation land. The same procedure will be repeated shortly for the common mode servo so this document will attempt to be as complete as reasonably possible. The document is divided into 3 sections, Computers, Cross Connect, and Electronics.
Computers
The mode cleaner board requires a new set of digital and analog channels as well as a bit of statecode for setting the gain bits. The database was largely imported from LLO with the channel names changed from L1: to C1: and the card and channel numbers for the XY220, 3113 and 4116 set appropriately. Since the MC board takes an entire XY220 to run, most of the bo (bo = "bit out") output fields could be left as they were with no changes (or so we think at the time of this writing).
Latch.st state code
The MC board has digitally addressable gain stages whose bits must be set and then latched so that the gain see the complete digital word at one time and no intermediate bad words. This feat of derring-do is accomplished by a state-code sequencer called latch.st run on the c1iool0 IOC. As a first step, we had to get the latch code compiled for the IOC's motorola processor running VxWorks, and of course, only one machine in the LIGO caltech universe is capable of cross-compiling VxWorks code. The instructions for compilation were supplied by Alex Ivanov:
- ssh to luna and copied files from LHO to ~aivanov/latch directory.
- setenv EPICS_BASE /opt/CDS/d/epics/release/r3.12.2/base
- setenv WIND_BASE /opt/CDS/a/vw/5.2
- setenv PATH /opt/CDS/a/vw/5.2/gnu/solaris.68k/lib/gcc-lib/m68k-wrs-vxworks/cygnus-2.2.3.1:/opt/CDS/d/epics/release/r3.12.2/base/bin/solaris:$PATH
- make latch.o
latch.st was modified so that the GAIN input and BIT SET output variables corresponded to C1 channels and not to LLO channels. In order to load the latch code here at caltech, we added two lines to the startup.cmd file,
ld < latch.o
seq &latch_bits
The first line loads the latching code and the second line tells the EPICS sequencer to start the code.
Modecleaner database
As for the latch, the c1mcservo.db database was copied over from LLO and all the variable names changed to correspond to the 40m universe. Besides changing L1 to C1, we had to ensure that the channels were correctly assigned to XY220 digital output, 3113 analog input, and 4116 analog output VME cards. We added a third XYCOM 220 to the VME crate so all the digital output card numbers were changed to #C2. We also wired the analog input and outputs to slots different here from LLO so the particular card and channel numbers were changed appropriately. Finally we removed all the channels we recognized as old MC channels from the ioo.db database.