SOLAR_MODE_CALIBRATION

Available as of PLC runtime system:	V1.3 and above
Included in library:	Solar_AC500_V22.lib
Type	Type_Function_Block_No_History
Group	Package of Function Blocks for different control modes

This Function Block represents an operation mode that allows to calibrate the tracker reference point.

This function is necessary to calibrate the reference point (Z) when incremental encoders are used for the first time.

Sequence of the calibration process.

Option 1:

1. Move the tracker by using SOLAR_MODE_MANUAL to a position that let you to measure that position easily.

2. Get the angular position by using a high accuracy measurement device. Store this value in POS_CALC variable.

3. Enabling Function Block to start calibrating process, then:

   • System will be moved automatically towards reference point.
   • System will stop as soon as reference point (Z) is reached. Encoders position function will stored the calibrating value at Z_VALUE.

   ⇒

   Calibrating process finished.

Option 2:

On the other hand, if you are not able to determinate tracker position by using a high accuracy measurement device, it is possible to use a simple sun sensor to determinate the correct tracker position.

Proceed as follow:

1. Move the tracker using SOLAR_MODE _MANUAL to a position ahead of the sun.

2. Using a sun sensor, you have to wait until tracker will be focused. At this moment you store the calculated solar position (obtained by using a sun position algorithm).

3. Enabling Function Block to start calibrating process, then:

   • System will be moved automatically towards reference point.
   • System will stop as soon as reference point (Z) is reached. Encoders position function will stored the calibrating value at Z_VALUE.

   ⇒

   Calibration process finished.

Note

Option 2 needs a sunny day to complete the process.

Figure below shows the logical sequence that implements both options:

Figure below shows the logical sequence that implements SOLAR_MODE_CALIBRATION for Type 1 & Type 2:

Figure below shows the logical sequence that implements SOLAR_MODE_CALIBRATION for Type 3 & Type 4:

Type 1: Using encoder reference point Z_PULSE to determinate home position.

First movement: Negative direction (left):

At the beginning, system is located at point 1 and limit switch is not active yet. When zACTIONTYPE1 is enabled, JOG_BWD is set to TRUE. As soon as shows rising edge, home position has been reached and system stops its movement at point 2.

If system is located between Z_PULSE and LIMIT_SWITCH positions, SOLAR_MODE_CALIBRATION operates as picture below shows:

Type 2: Using encoder reference point Z_PULSE to determinate home position.

First movement: Positive direction (right):

At the beginning, system is located at point 1 and Z_PULSE is not active yet. When SOLAR_MODE_HOMING is enabled, JOG_FWD is set to TRUE. As soon asZ_PULSE shows rising edge, home position has been reached and system stops its movement at point 2.

If system is located between Z_PULSE and LIMIT_SWITCH positions, SOLAR_MODE_CALIBRATION operates as picture below shows:

Example: SOLAR_MODE_CALIBRATION + Encoder

Note

ModeCalibrate.Z_PULSE = CD522Encoder.RDY_TO_CALIB

Type 3: Using Z_PULSE and cam switch to determinate home position.

First movement: Positive direction (right):

Home position has been reached when rising edge of the signal Z_PULSE is detected. Then, movement is stopped. On the other hand, if system is located at the end of its movement range and Z_PULSE signal is set to TRUE (see picture below) home position is reached as follow:

Type 4: Using Z_PULSE and cam switch to determinate home position.

First movement: Negative direction (left).

Home position has been reached when rising edge of the signal Z-PULSE is detected. Then, movement is stopped. On the other hand, if system is located at the end of its movement range and Z_PULSE signal is set to TRUE (see picture below) home position is reached as follow:

Example: SOLAR_MODE_CALIBRATION + Encoder.

Note

ModeCalibrate.Z_PULSE = CD522Encoder.Z_PULSE

• Input Description
• Output Description
• Function Call in IL
• Function Call in ST