Interfaces
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Protocol of an addressable EMAX / EMAL:
General format of a message to the EMAX or EMAL:
0x02 Byte1 Byte2 Byte3 0x03
STX check ETX
0x02 (STX) starts a message
0x03 (ETX) close the message
Byte3 (check) is the arithmetic sum of 0x02(STX), Byte1 and Byte2.
ETX is not included in the checksum
0x04 characterizes the message as position-request
i is the address of the requested EMAX / EMAL (i = 0x0b... 0x7f).
The position value consists of 3 byte:
PosLow (bit 0… bit 7), PosMid (bit 8… bit15), PosHigh (bit16...bit23).
Bit 0 has the value10 µm. Position-values are always smaller than 0xffff00.
Please note: The last byte is no ETX, like in all the other messages, but the EMAX / EMAL address.
Interrogation of the address of an EMAX / EMAL:
Connect always only a single EMAX / EMAL to be interrogated via RS422/RS232 converter to COM port of a
PC.
Note: The combination 0xff 0xff does not appear in normal mode for position answers of EMAX / EMAL (directly
after STX) It is a sign for a special message not a position (in this case with 0x0b <= i <=0x7f it is the answer
to the interrogation of the address).
Negative answer: If one of the described operations failed for some reasons, the EMAX / EMAL encoder will give
a negative answer with a concerning error code.
General format of a message from the EMAX or EMAL:
0x02 Byte1 Byte2 Byte3 Byte4
STX
Position-request from the EMAX or EMAL with address i:
Message to the EMAX or EMAL
0x02 0x04 i check 0x03
STX check ETX
Answer of the requested EMAX or EMAL:
0x02 PosHigh PosMid PosLow EMAX address
Message to the EMAX or EMAL:
0x02 0x05 0x05 0x0c 0x03
STX address request check ETX
Answer of the EMAX or EMAL:
0x02 0xff 0xff i 0x03
STX EMAX address ETX
EMAX or EMAL answers:
0x02 0xff 0xff Err 0x03
STX 0xff 0xff Error Code ETX
With Err = 0x04... 0x0a
