Technical data

MESOMATIC Automation und Messtechnik GmbH D-71394 Kernen
4.4.3. Shortened bidirectional channel (identifier 0xBF)
This channel is recommended to be used only if problems occur when using the bidirectional
32 Byte channel with the identifier 0xFF, e. g. if it is impossible to ensure consistency
over more than 16 Bytes on the SPC. The shortened 16 Byte channel (identifier 0xBF)
corresponds to the 32 Byte channel (identifier 0xFF), but is limited to a length of 16
Bytes. Responses of the serial interface of the DK900 are restricted to a length of 15
Bytes.
Telegram from the Profibus Master to the DK900 (command, instruction):
Byte Description
0 Control byte
Bit 7 Toggle bit, after the start of the DK900 the toggle bit is
= 0.
Bit 6 0, no meaning
Bit 5 0, no meaning
Bit 4 0, no meaning
Bits 3..0 Number of characters, starting with Byte 1
1 1st character to be transmitted
2..15 Subsequent characters
Table 5 Shortened bidirectional channel (Master ® DK900)
Telegram from the DK900 to the Profibus Master (response):
Byte Description
0 Control byte
Bit 7 Toggle bit
Bit 6 1=ACK, 0=NAK
Bit 5 1= · No valid response received via the internal serial
interface;
· or the command is not supported, e. g. "*X..."
· otherwise 0.
Bit 4 The length of the DK900’s response has been limited.
Bits 3..0 Number of characters, starting with Byte 1
1 1st character to be transmitted
2..15 Subsequent characters
Table 6 Shortened bidirectional channel (DK900 ® Master)
DK900 17