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Sloan Digital Sky Survey

2.5-meter Telescope Controls & Interlock System

Receiver/Splitter Chassis Input Table

Revised 4/7/2000


The following table lists the inputs into the receiver/splitter chassis for the 2.5-meter telescope axes control and interlock system.  Some of the inputs come directly from mechanical devices such as stop buttons, limit switches, etc.  Other inputs are provided by the interlock system programmable logic controller (PLC) based on the state of various system conditions.  The logic behind these inputs is graphically described in interlock system logic diagrams.

The receiver/splitter chassis provides the capability for bypassing each input channel.  Bypassing a channel effectively bypasses an interlock.  In several cases, bypassing a single channel effectively disables all interlocks protecting a particular telescope axis or system.  These instances are noted in the table.

The interlock system is carefully designed to protect the telescope.  Disabling all or part of this system may result in serious damage to the telescope. Bypassing interlocks must only be done after the relative logic diagram has been reviewed and the consequences of the bypass fully understood.

Questions regarding inputs into the receiver/splitter chassis, or to the interlock system in general, should be addressed to
John Anderson (630.840.4973), or Glenn Federwitz  (630.840.4836).


 
Slot CH Input Device Description Affects
1 0 tcc_ stop Provision for input from TCC to disable telescope motion. Not implemented. AZ,ALT,ROT Motion
1 cr_stop Stop Button in the 2.5-m Control Room AZ,ALT,ROT Motion
2 spare_s1_c2 spare channel N.U.
3 fiber_signal_loss Indicates the fiber optic signal from the main building is not functioning N.U.
4 n_wind_stop Stop Button on the north side of the windbaffle frame AZ,ALT,ROT Motion
5 n_fork_stop Stop Button on the northeast telescope fork AZ,ALT,ROT Motion
6 s_rail_stop Stop Button on the north railing - outside AZ,ALT,ROT Motion
7 n_rail_stop Stop Button on the south railing - outside AZ,ALT,ROT Motion
2 0 w_rail_stop Stop Button on the west railing - outside AZ,ALT,ROT Motion
1 n_lower_stop Stop Button on the north wall in the lower level AZ,ALT,ROT Motion
2 s_lower_stop Stop Button on the south wall in the lower level AZ,ALT,ROT Motion
3 e_lower_stop Stop Button on the east wall in the lower level AZ,ALT,ROT Motion
4 w_lower_stop Stop Button on the west wall in the lower level AZ,ALT,ROT Motion
5 s_fork_stop Stop Button on the north side of the windbaffle frame AZ,ALT,ROT Motion
6 spare_s2_c6 spare channel N.U.
7 spare_s2_c7 spare channel N.U.
3 0 alt_mtr_up_perm Permit from PLC Inhibits telescope altitude upward motion See logic diagram EB-355925 for details (Output from PLC to Splitter Chassis) Alt UP Motion
alt_mtr_up_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK DISABLES THE TELESCOPE UP DIRECTIONAL SOFT LIMIT.
1 alt_mtr_dn_perm Permit from PLC Inhibits telescope altitude downward motion. See logic diagram EB-355925 for details. (Output from PLC to Splitter Chassis) Alt DOWN Motion
alt_mtr_dn_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK DISABLES THE TELESCOPE UP DIRECTIONAL SOFT LIMIT.
2 alt_mtr1_perm Permit to telescope altitude motor #1 allowing bi-directional motion. (Hard Wired Signal) Alt Motor 1 Motion
alt_mtr1_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING***BYPASSING THIS INTERLOCK EFFECTIVELY DISABLES NUMEROUS INTERLOCKS PROTECTING TELESCOPE ALTITUDE MOTION. REFER TO LOGIC DIAGRAM EB-355925 FOR DETAILS.
3 alt_mtr2_perm Permit to telescope altitude motor #2 allowing bi-directional motion. (Hard Wired Signal) Alt Motor 2 Motion
alt_mtr2_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING***BYPASSING THIS INTERLOCK EFFECTIVELY DISABLES NUMEROUS INTERLOCKS PROTECTING TELESCOPE ALTITUDE MOTION. REFER TO LOGIC DIAGRAM EB-355925 FOR DETAILS.
4 wind_alt_mtr_perm Permits bi-directional motion of the windbaffle altitude motors. See logic diagram EB-355925 for details. (Hard Wired Signal) Alt Wind Motion
wind_alt_mtr_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK CHANNEL EFFECTIVELY DISABLES NUMEROUS INTERLOCKS PROTECTING WINDBAFFLE ALTITUDE MOTION. REFER TO LOGIC DIAGRAM EB-355925 FOR DETAILS.
5 alt_plc_perm Permit from the PLC that allows telescope altitude motion. See logic diagram EB-355925 for details. (Output from PLC to Splitter Chassis) Alt Motion
alt_plc_perm-in (Input to PLC) Status of splitter chassis channel output
6 wind_alt_plc_perm Permit from PLC that allows windbaffle altitude motion. See logic diagram EB-355925 for details. (Output from PLC to Splitter Chassis) Alt Wind Motion
wind_alt_plc_perm-in (Input to PLC) Status of splitter chassis channel output
7 az_stow_3a The 3rd contact from Stow A this with Stow B lets the Interlocks know that the Telescope is in the stow range Building Motion
4 1 az_mtr_cw_perm Permit from PLC allowing telescope clockwise motion. Refer to logic diagram EB-355926 for details. (Output from PLC to Splitter Chassis) AZ CW Motion
az_mtr_cw_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK DISABLES THE TELESCOPE CW DIRECTIONAL SOFT LIMIT.
2 az mtr_ccw_perm Permit from PLC allowing telescope counterclockwise motion. (Output from PLC to Splitter Chassis) AZ CCW Motion
az mtr_ccw_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK DISABLES THE TELESCOPE CCW DIRECTIONAL SOFT LIMIT
3 az_mtr1 perm Permit to telescope azimuth motor #1 allowing bi-directional motion. (Hard Wired Signal) AZ Motor 1 Motion
az_mtr1 perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING***BYPASSING THIS INTERLOCK EFFECTIVELY DISABLES NUMEROUS INTERLOCKS PROTECTING TELESCOPE AZIMUTH MOTION. REFER TO LOGIC DIAGRAM EB-355926 FOR DETAILS.
4 az_mtr2_perm Permit to telescope azimuth motor #2 allowing bi-directional motion. (Hard Wired Signal) AZ Motor 2 Motion
az_mtr2_perm-in (Input to PLC) Status of splitter chassis channel output
  ***WARNING***BYPASSING THIS INTERLOCK EFFECTIVELY DISABLES NUMEROUS INTERLOCKS PROTECTING TELESCOPE AZIMUTH MOTION. REFER TO LOGIC DIAGRAM EB-355926 FOR DETAILS.
5 wind_az_mtr_perm Permits bi-directional motion of the windbaffle azimuth motors. See logic diagram EB-355926 for details. (Hard Wired Signal) AZ Wind Motion
wind_az_mtr_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK CHANNEL EFFECTIVELY DISABLES NUMEROUS INTERLOCKS PROTECTING WINDBAFFLE AZIMUTH MOTION. REFER TO LOGIC DIAGRAM EB-355926 FOR DETAILS.
6 wind_az_plc_perm Inhibits windbaffle azimuth motion unless the 15-deg stop is engaged. (Output from PLC to Splitter Chassis) AZ Wind Motion
wind_az_plc_perm_in (Input to PLC) Status of splitter chassis channel output
7 az_stow_3b The 3rd contact from Stow B this with Stow A lets the Interlocks know that the Telescope is in the stow range Building Motion
5 0 rot_mtr_cw_perm PLC permit that allows rotator motion in clockwise direction. (Output from PLC to Splitter Chassis) Rot CW Motion
rot_mtr_cw_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK DISABLES THE ROTATOR CW DIRECTIONAL SOFT LIMIT.
1 rot_mtr_ccw_perm PLC permit that allows rotator motion in counterclockwise direction. Disabled if soft limit reached. (Output from PLC to Splitter Chassis) Rot CCW Motion
rot_mtr_ccw_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK DISABLES THE ROTATOR CCW DIRECTIONAL SOFT LIMIT.
2 rot_mtr_perm Permit enabling rotator bi-directional motion. (Hard Wired Signal) Rot Motion
rot_mtr_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK CHANNEL EFFECTIVELY DISABLES ALL HARD LIMITS PROTECTING ROTATOR MOTION. REFER TO LOGIC DIAGRAM EB-355925 FOR DETAILS.
3 spare_s5_c3 spare channel N.U.
4 bldg_perm Permit enabling building motion. (Hard Wired Signal) Building Motion
bldg_perm_in (Input to PLC) Status of splitter chassis channel output
  ***WARNING*** BYPASSING THIS INTERLOCK DISABLES THE BUILDING MOTION INTERLOCKS. REFER TO LOGIC DIAGRAM EB-355939 FOR DETAILS
5 rot_plc_perm Telescope rotator motor overcurrent interlock. Disables rotator motion if motor overheating sensed. (Output from PLC to Splitter Chassis) Rot Motion
rot_plc_perm_in (Input to PLC) Status of splitter chassis channel output
6 hatch_cls Hatch door switches prevent building motion unless hatch doors are closed. Building Motion
7 alt_les_2d5_limit Alt has to be below 2.5 degrees for building motion Building Motion
6 0 alt_grt_0d3_limit Altitude lower "hard" stop. Disables telescope and windbaffle drive motors. Alt Motion
1 alt_locking_pin_out Locking pin "not out" Disables telescope and windbaffle Altitude drive motors Alt Motion
2 alt_les_90d5_limit Altitude upper "hard" stop. Disables telescope and windbaffle Altitude drive motors. Alt Motion
3 bldg_on_alt Signal that indicates that the building is on. Used on Altitude Axis Alt Motion
4 az_109_131_limit_1 The 1st contact from the Azimuth building "on" motion "hard" limits Alt Motion
5 alt_grt_18d6_limit_1 The 1st contact from the Altitude "hard" limit for the railing Alt Motion
6 az_stow_1a The 1st contact from Stow A this with Stow B lets the Interlocks know that the Telescope is in the stow range Alt Motion
7 az_stow_1b The 1st contact from Stow B this with Stow A lets the Interlocks know that the Telescope is in the stow range Alt Motion
7 0 alt_grt_83_limit_1 The 1st contact from the Altitude "hard" limit for full azimuth motion with building "on" Alt Motion
1 bldg_clear_alt Signal that indicates that the building is off far enough for safe operation. Used on Atitude axis Alt Motion
2 az_stow_2a The 2nd contact from Stow A this with Stow B lets the Interlocks know that the Telescope is in the stow range Alt Motion
3 az_stow_2b The 2nd contact from Stow B this with Stow A lets the Interlocks know that the Telescope is in the stow range Alt Motion
4 deg_15_stop_ext 15 degree stop fully extended status Alt Motion
5 alt_grt_18d6_limit_2 The 2nd contact from the Altitude "hard" limit for the railing Alt Motion
6 alt_slip Slip detection trip output signal Alt Motion
7 alt_velocity_limit Velocity limit output signal Alt Motion
8 0 az_dir_cw Azimuth Clockwise direction switch Az Motion
1 az_dir_ccw Azimuth Counter Clockwise direction switch Az Motion
2 az_neg_170a_cw The 1st contact from the Azimuth 170 degree Clockwise "hard" limit switch Az Motion
3 az_pos_410a_ccw The 1st contact from the Azimuth 410 degree Counter Clockwise "hard" limit switch Az Motion
4 az_neg_170b_cw The 2nd contact from the Azimuth 170 degree Clockwise "hard" limit switch Az Motion
5 az_pos_410b_ccw The 2nd contact from the Azimuth 410 degree Counter Clockwise "hard" limit switch Az Motion
6 spare_s8_c6 spare channel N.U.
7 spare_s8_c7 spare channel N.U.
9 0 alt_grt_18d6_limit_3 The 3rd contact from the Altitude "hard" limit for the railing AZ Wind Motion
1 bldg_on_az Signal that indicates that the building is on. Used on Azimuth axis Az Motion
2 az_109_131_limit_2 The 2nd contact from the Azimuth building "on" motion "hard" limits Az Motion
3 alt_grt_83_limit_2 The 2nd contact from the Altitude "hard" limit for full azimuth motion with building "on" Az Motion
4 bldg_clear_az Signal that indicates that the building is off far enough for safe operation. Used on Azimuth axis Az Motion
5 spare_s9_5 spare channel N.U.
6 az_slip Slip detection trip output signal Az Motion
7 az_velocity_limit Velocity limit output signal Az Motion
10 0 rot_dir_cw Rortator Clockwise direction switch Rot Motion
1 rot_dir_ccw Rotator Counter Clockwise direction switch Rot Motion
2 rot_neg_200a_cw The 1st contact from the Rotator 200 degree Clockwise "hard" limit switch Rot Motion
3 rot_pos_380a_ccw The 1st contact from the Rotator 380 degree Counter Clockwise "hard" limit switch Rot Motion
4 rot_neg_200b_cw The 2nd contact from the Rotator 200 degree Clockwise "hard" limit switch Rot Motion
5 rot_pos_380b_ccw The 2nd contact from the Rotator 380 degree Counter Clockwise "hard" limit switch Rot Motion
6 rot_slip Slip detection trip output signal Rot Motion
7 rot_velocity_limit Velocity limit output signal Rot Motion


Last updated on 4/7/2000
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