There are four antenna axes encoders, two for azimuth and two for elevation, that are read with two ik320 VME modules installed in vac1. The two ik320 VME modules are named AE0 and AE1 (for Antenna Encoders 0 and 1). AE0 reads the first Azimuth and Elevation encoders, while AE1 reads the second Azimuth and Elevation encoders.

With the new VME reading of the axes encoders is no necessary to carry out encoders reset as often as with the old CAMAC system. The reasons why encoders reset were more necessary with the previous CAMAC connection were:

  1. Sporadically, asynchronous reset were executed because some bug in the control program.
  2. If the antenna suffered a fast movement, for instance because the wind, the CAMAC module was not able to keep the incremental counting of the encoders.

Nevertheless, with the new VME system could be necessary to carry out an encoder reset, for instance if a power failure or a local reset of the vac1 micro. In that case reset the encoders proceeding as follow.

  1. If the int_ant interrupt is running in vac1, must be stopped.

    • to know if int_ant is running check it with the command

      • lsmod

      if int_ant is running, first stop the process evItSlow doing the following: identify its PID with the command

      • ps -ax |grep evItSlow

      and with the PID identified
      • kill PID

      after that, remove the antenna interrupt with the command
      • rmmod int_ant

  2. Monitor in vac1 the status bytes and the encoders reading by means of the program

    • /home/penalver/ik320, choose option 7 (for next steps it is more confortable to run ik320 in two different windows)

    • If the status byte is 04 or 05 usually indicates that the encoder reading is correct. Leave the program running while executing the following steps

  3. Move the antenna to the stow position (azimuth and elevation) to proceed with the encoders reset
  4. Run the program /home/penalver/ik320 in vac1 and choose option 0 to select the ik320 module, AE0 or AE1

  5. In the program /home/penalver/ik320 choose the option 1 to initialise the ik320 VME module

  6. In the program /home/penalver/ik320 choose option 2 to execute a POST (Power On Self Test) of the ik320 VME module

  7. In the program /home/penalver/ik320 choose option 3 to reset the axis 1 (Azimuth) of the ik320 VME module. The axis 1 must be reset before the axis 2. The status byte must change to 20 indicating that the module is ready for resetting when crossing the reference position. If after several tries was not possible to get the status 20, do a hardware reset of vac1 from servo room and start from the beginning.

  8. Move azimuth at +3% velocity until the status byte changes to 04 or 05, then the reset is done

  9. In the program /home/penalver/ik320 choose option 4 to reset the axis 2 (Elevation) of the ik320 VME module. The axis 2 must be reset after the axis 1, but not immediately. The status byte must change to 20 indicating that the module is ready to be reset when crossing the reference position.

  10. Move Elevation at +3% velocity until the status byte changes to 04, then the reset is done

  11. If necessary to reset the other ik320 VME module proceed from step 3.

If the encoder reset doesn't proceed as expected repeat from step 6. for both axes or from step 7. or 9. for only one axis.

Don't forget that when running the program /home/penalver/ik320, if by mistake options 2, 3 or 4 are chosen, the encoder reset must be repeated from that option.

ResetEncoders (last edited 2010-09-27 09:00:45 by localhost)