MECAR won't turn on due to a Bypass Loop trip
Even though the Bypass Loop is actually up (other independent sources) MECAR sees the Bypass Loop Status as tripped. This is preventing MI turn on.
#1 Updated by Kevin Martin over 5 years ago
In order to get the MI on while we diagnose the problem with the Bypass Status I am going to desensitize the SPAM real time code to the Bypass Loop being down. This will be temporary while we fix the problem of the Bypass Loop Status always showing as tripped.
Files modified: mecar.h
#2 Updated by Kevin Martin over 5 years ago
- % Done changed from 0 to 100
The VME card that handles the Bypass Loop Trip status input is the VMIC2510. It's a 64 bit DIO card with has eight 8-bit bi-directional ports. The Bypass Loop Trip status is hooked to one of the ports (DR2) which is programmed to be an input port. The Beam Abort output uses another port (DR3) which is programmed to be an output port.
After desensitizing the code to the Bypass Loop Status we were able to establish a MI ramp. But when MI experts attempted to run beam they couldn't because MECAR was asserting a Beam Abort. However, according to MECAR's internal status it wasn't asserting a Beam Abort.
Because the Beam Abort uses the same VME card it was decided that we should swap the VMIC2510 out and replace it with the VMIC2510 from the backup MECAR chassis located in the micropit.
However, after replacing the card the problems didn't go away. I then determined that the 64 conductor cable had been, at some point, erroneously hooked to the front panel P4 connector rather then the P3 connector, which it should have been hooked to. I move the cable and the problems went away!
It is still possible that the original VMIC2510 has a problem so we will be testing it to determine this.