X20 system modules • Digital signal processing modules • X20DS1928
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X20 system User's Manual 3.10
4.16.5.10.9.3 EnDat - Read additional information
In addition to the identification data, other information can also be accessed from the encoder. However, the fol-
lowing algorithm requires exact knowledge of the encoder's memory structure and the EnDat specification.
Configuration
There are four different channels that can be operated during a cycle. One register per channel each is used for
configuration, (i.e. determines which data is read from the encoder and mirrored on the respective Info byte).
EnDatInfoCmd
Names (pChannelName):
EnDatInfoCmd01
EnDatInfoCmd[02…04]
The "EnDatInfoCmd" register controls which data is processed on the corresponding Info byte for each channel.
The register consists of up to four separate 8-bit values.
Data type
Values
4x UDINT
see bit structure
Bus controller default setting: 0
Bit structure:
Bit
Name
Information
00-07
Command
Selects the response section
08-15
Memory area code
MRS code
Parameters not in blocks
Parameters arranged in blocks
16-23
Memory ID
Parameter number
Block number
24-31
Memory ID
-
Parameter number
There is a difference when querying data from an encoder using an EnDat 2.1 command or an EnDat 2.2 command.
When querying encoder data with an EnDat 2.1 command (0x04 and 0x06) the parameter number and (optionally)
the block number must be specified in addition to the MRS code.
When querying the memory with an EnDat 2.2 command, the parameter number and block number are not required.
The module consecutively sends all four words of the memory area, which was selected using the MRS code. The
right command must be selected depending on which of the four response bytes is needed.
Memory area code:
The code to be defined is identical to the MRS code for the encoder memory. The EnDat specification has left
a few of the encoders memory areas undefined and available for future developments. This is why a clear and
reliable explanation cannot be provided here.
More detailed information can be found in the encoder's manual or by referring to the latest EnDat specification.
Parameter number:
EnDat 2.1 requires the corresponding parameter number to be entered in order to specifically address the desired
parameter in the encoder memory. Older EnDat versions did not divide the encoder memory into blocks. This is
why there are memory areas that can be selected without specifying a block number. In this case, the parameter
number must be entered on the third byte.
More detailed information can be found in the encoder's manual or by referring to the latest EnDat specification.
Block number:
To expand the address range of the encoder memory, additional block numbers were added starting at the second
section. If the desired parameter is located in this blocked area, then the block number must be specified on the
third byte. In this case, the parameter number is indicated on the fourth byte.
More detailed information can be found in the encoder's manual or the latest EnDat specification.
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