Positioning module IMD20, IMD40
Description of the drive module
character
Control
Meaning
C
SDO query (is received by the module)
B
SDO response (is sent by the module)
E Boot-up
message
1 Emergency
telegram
F
Error during transfer
F1: received too few characters
F2: checksum error
F3: received too many characters
F4: error during the conversion of the characters
The checksum is formed on the basis of the 1 ... n data bytes (not the ASCII characters). It has to be
of no importance for the forming of the checksum.
nd 0x46).
d 256 ) or
= - ( Division remainder of ((Byte1 + Byte2 + ... + Byte_n) : 256))
adecimal
number)
0 of 0xFF10 are transferred as the checksum before
taken into account that the control character is
This only concerns the “pure” data bytes that are to be transferred. The checksum also has to be
converted into ASCII characters again, before it is sent. This transfer protocol is applicable for both
directions of transfer, i.e. both for the reading and the writing process.
Conversion of the data bytes into ASCII signs: e.g. 0x3F = '3' and 'F' (0x33 a
Checksum = - ( (Byte1 + Byte2 + ... + Byte_n) mo
In the following, example 2 is used to show why a checksum of 0x10 (hexadecimal number) is
created.
C
2F 60 60 00 01
10
CR
The control character ‚C’ and Carriage-Return ‚
CR
’ are not taken into account for the calculation.
Checksum
=
- (0x2F + 0x60 + 0x60 + 0x00 + 0x01)
(hexadecimal number)
=
- (47 + 96 + 96 + 0 + 1)
(decimal number)
=
-
240
(decimal
number)
=
- Division remainder of (240 : 256)
(decimal number)
=
-240
(decimal
number)
=
0xFF10
(hexadecimal
number)
=
0x10
(hex
The two characters 1 and 0 for the last byte 0x1
the carriage return.
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