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Zelio Logic roof module

Zelio roof control

This is a roof module based on a Zelio Logic PLC. To view and use it, you need to download Schneider Zelio logic editor, which runs under Wine in Linux. Ask me for details if you cannot get it running.

The program is designed for a clamshell type roof with two moving halves, four end-of-path sensors and two motors. If your needs are different, please either help yourself or contact Petr Kubanek with questions. The PLC is assumed to have an Ethernet modbus output module attached - SR3NET01BD for PC-PLC communication. Please see description of registers at the end of the page.

There is a picture of front panel. In our experience, nothing beats hardware switches when it comes to reliably blocking roof opening by staff, including not-so-computer maniacs. The cost of the switches, cables and box was about 1000 ZAR ~ 95 EUR, and the electronics inside (Zelio, ..) was about 500 EUR.

Roof front panel

The program has the following characteristics:

  • auto/manual selection switch
  • close/open switch for manual operation
  • four switch inputs for end-of-path control
  • control for four motor relays - two per motor (open and close direction)
  • attached ethernet module with dead-man's handle functionality (i.e. if PC stop responding, roof will close).
  • rain input (when 1, it is not raining)
  • configurable timeout for roof closing/opening
  • configurable timeout for time between roof closing/opening (change of direction)
  • independent operation of both halves of the roof, governed by power sensing input (I9)
  • any timeout (opening or closing) prevents the roof from opening. Timeouts must be reset manually, either by pressing and releasing the emergency switch, or by power cycling the unit. The roof can attempt to close while in timeout.


  • I1 Manual/Auto operation. If on, the roof is operating automatically, and will ignore inputs from I2, accepting only those from the Ethernet controller.
  • I2 Open/Close switch. Commands the dome to open (on) or close (off). Only effective if I1 is in manual mode (i.e. off).
  • I3, I4, I5, I6 Inputs for end-of path switches. Please see the provided description for details. Inputs should be on when the roof is at the corresponding position, and otherwise off. Left and right half descriptions can be changed as you wish, with left opening first and closing last.
  • I7 Good weather input. On indicates observation is possible, while off signifies bad weather.
  • I8 Emergency stop. If engaged, the roof halts all operations until the reset is emergency signal is removed.
  • I9 Power sensing. If on, grid electricity is available.


  • Q1,Q2,Q3,Q4 open and close motor relays. If one, given motor is command open/close.
  • Q8 is engaged in emergency situation - e.g. when a timeout occurs. It is reset by pressing emergency stop or power cycling the unit.
  • Q9 is extra, currently used to power-cycle an external all-sky camera (1 - cut power)

Ethernet inputs

  • J1XT1 7 low bits are used for timeout control. So 127 seconds is maximal timout for roof control. The most significant bit (16) is used for weather override - if set to 1, roof will operate from computer even if it is raining. Bit 15 (4000) is used for control of Q9 switch.
  • J2XT1 Dead man's handle. The ethernet module must receive changing 0 and 1 s wiithin time specified in J1XT1. If 0 or 1 is not received, module will command roof to close. On model with compressor (see * in output description), 8 bits (8-15) are used for closing timeout control. Bit 16 is then a bit which override default roof value with value specified in bits 8-15.

Ethernet outputs

  • Q1XT1 State of right half of the roof.
  • Q2XT1 State of left half of the roof.
  • Q3XT1 Number of seconds remaining before dead man's handle times out.
  • Q4XT1 State of various emergency and other signals

Roof states reported in ethernet outputs

Each output is treated as a bit value, with the bits given the following meanings:

  1. 0001 not used
  2. 0002 not used
  3. 0004 state of end-of-path open switch
  4. 0008 state of end-of-path close switch
  5. 0010 not used
  6. 0020 state of final block for opening
  7. 0040 state of final block for closing
  8. 0080 timeout during closing
  9. 0100 timeout during opening
  10. 0200 motor commanded opening
  11. 0400 motor commanded closing
  12. 0800 opening blocked
  13. 1000 closing blocked

The device state (Q4XT1):

  1. 0001 state of manual/auto switch (I1)
  2. 0002 state of close/open switch (I2)
  3. 0004 timeout occured - emergency declared
  4. 0008 power sensing (I9) - not present on compressor models
  5. 0010 rain declared
  6. 0020 compressor running - only on model with compressor
  7. 0040 not used
  8. 0080 not used
  9. 0100 not used
  10. 0200 not used
  11. 0400 not used
  12. 0800 compressor (B2) model *
  13. 1000 weather state - 1 if weather is favorable for observing
  14. 2000 ignore rain during opening - a known problem for the opening on some domes. This feature is not present on compressor models.
  15. 4000 emergency button pushed
  16. 8000 state of deadman signal
hw/zelio.txt · Last modified: 2020/09/28 23:30 by pkubanek