SOLAR_ENCODER_CD522_SSI_GRAY¶
| Available as of PLC runtime system: | V1.3 and above |
| Included in library: | Solar_AC500_V22.lib |
| Type | Function Block without historical values . |
| Group | Package of functions to get the sun position |
Function Block to easily integrate, with the CD522 card, absolute encoders SSI GRAY as positioning sensors for Solar Trackers.
The module CD522 can be used in 12 different configurable operating modes. The operating mode is configured in PLC Configuration using module parameters. After that, it is activated during the initialization phase (power-on, cold start, warm start).
In order to configure and use the function counter of module CD522, different operating modes are available. The Function Block CD522_SSI should be used configuring the parameter 6 or 14 (“Mode counter 0” or “Mode counter 1”) with the operating mode:
Operating Mode 14 “SSI, absolute encoder”
Should be specified in PLC Configuration; parameter “Mode counter” in order to use absolute encoder with SSI interface.
The module CD522 provides 2 SSI absolute encoder functions. There is an interface for absolute angle and linear encoders (displacement measurement systems).
It allows the transmission of absolute position information through a serial data transfer.
The transmission is based on synchronous serial communication. The device sends a clock signal to the encoder and synchronously, the encoder returns the positioning data from the most significant to the less significant bit.
The synchronization for a new data stream is based on time without clock pulse. This quiet time depends on the encoder.
Chronogram with data organization with the clock pulse:
The resolution of the encoder device (see technical data from manufacturer) can be set (with configuration, number of bits, etc.) in PLC Configuration, parameter “SSI resolution in bit” (see figure below).
In Control Builder Plus V2.0 and above :
The trace B of module CD522 is switched as output signal (differential). On the rising edge of the signal, the sensor shifts a new value, starting from the most significant bit.
The clock frequency can be set to 200 kHz, 500 kHz, and 1 MHz and should be specified in PLC Configuration, parameter “SSI frequency” (see figure below).
In Control Builder Plus V2.0 and above:
SSI Polling Time Definition
The complete read sequence is launched regularly by the module CD522. The interval between each sequence can be set from 1 ms to 255 ms in PLC Configuration, parameter “SSI polling time” (see figure below).