Burkert Type 8056 User Manual
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RS232_485_ETP_MODBUS_BU_REV02.doc
The syntax for inserting the code is: “ACODE=n” with n=access code L2
The lifecycle of the code is limited at the execution of the string command that following the code.
After the acquisition of the command the access level return at default status.
Is necessary to insert the code level every time the command or the list of the command request the insertion of the
code access greater than the default level.
If the level L2 of the converter is set to 0, then is not necessary to insert the code L2.
When the access code is not sufficient for the command, the converter return the following error code:
5:ACCESS ERR
Example of string with command for code level L2=12345 and command for reading model a software version of the
converter:
“ACODE=12345,MODSV?” + chr(13)
3.3.8.
DATA BLOCK FORMAT
Communication takes place through data blocks or packs of variable length which do not exceed 256 bytes overall. A
data block or pack is composed thus::
ADDRESS TO, Containing the address of the device the block is sent to;
ADDRESS FROM, Containing the address of the device which sent the block;
BLOCK CODE, Containing the code that it indicates if after this block given there is a successive block;
BLOCK LENGTH, Containing the length of the data block in bytes
BLOCK DATA, The block of data of variable length from zero to 250 bytes
CRC CHECKSUM BYTE, Calculated in the following way:
4. CRC initialised to zero
5. CRC rotated to the left by one bit
6. CRC = CRC + block bytes
The process is repeated starting from point 2. for all the block bytes, excluding CRC..
NOTE:
The CRC must be subjected to an operation of
rotation to the left
and not just a simple
shift
operation.
The difference is shown in the following example:
byte value:
10100010
shifting :
1 <= 0100010 <= 0
rotating: 1 1 <= 0100010 <= 1
NOTE:
The code to insert in BLOCK CODE can have the following values:
90 decimal (5A hex)
91 decimal (5B hex)
Insert 90 decimal when BLOCK DATA length is smaller or equal to 250 characters
If the length of the block data is greater than 250 characters, split the block data in packets of 250
characters.
Every packets with BLOCK DATA of 250 characters have BLOCK CODE equal to 91 dec.
The last block of data with numbers of byte smaller or equal to 250 have BLOCK CODE with 90 dec.