BECKHOFF AX2000 PROFIBUS DP communication profile - Manual (Page 43)

6 Appendix
6.1 Example telegrams
6.1.1 Zero telegram (for initialization)
At the beginning of PROFIBUS communication via the parameter channel and after communication
errors, a zero telegram should be sent:
Byte 1 2 3 4 5 6 7 8
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
PKE IND PWE
The AX2000/2500 answers, by likewise setting the first 8 byte of the telegram (PKW) to zero.
6.1.2 Setting the Opmode
After switch-on or a reset (coldstart) the AX2000/2500 is in the PROFIBUS operating mode -126, in
which it cannot perform any motion functions. For example to carry out positioning operations
(motion tasks, jogging, homing), it must be set to the position-control mode.
The procedure to do this is as follows:
a) Set the control word Bit 10 (PZD1, Bit 10) to 0.
This invalidates the process data for the AX2000/2500.
Byte 9 10 11 12
xxxx x0xx xxxx xxxx xxxx xxxx xxxx xxxx
STW HSW
b) Transmit PNU 930 through the parameter channel to set the operating mode.
Byte 1 2 3 4 5 6 7 8
0011 0011 1010 0010 xxxx xxxx xxxx xxxx 0000 0000 0000 0000 0000 0000 0000 0010
PKE IND PWE
The bits in the PKE section of the PKW have the following significance:
Bit 0 to 10 = PNU 930, Bit 12 to 15 = AK 3 (see also Chapter 3.1.1)
The AX2000/2500 sends a response telegram with AK = 2 and mirrors (identical)
the values for the PNU (parameter number) and PWE (parameter value).
c) Switch on the new operating mode by setting the control word (STW) Bit 10 to 1.
This validates the process data.
If, for example, point a) is not observed, the AX2000/2500 transmits a negative answer: (response
ID=7)
Byte 1 2 3 4 5 6 7 8
0111 0011 1010 0010 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0001 0001
PKE IND PWE
And the number that is transferred in the PWE section represents the error number, and can be loo-
ked up in the table in Chapter 3.1.1.2. In this case, error no. 17, “Task impossible because of opera-
ting state” will be signaled.
PROFIBUS for AX2000/2500 43
BECKHOFF
12/05
Appendix