Omron 3G3AX-MX2-PRT-E User Manual page 46

Accessing Parameters
!Caution
4-5-2-1 Opening and Closing a DP-V1 Channel
4-5-2-2 DP-V1 read/write sequence
32
Do not access Inverter parameters while the Inverter is being re-initialized
(Refer to the MX2-A@ Inverter manual section 6-3). Accessing parameters
during a re-initialization will cause the Inverter to go into an undefined state.
Before the PROFIBUS master can exchange information with the Option
Board, the PROFIBUS master has to open a DP-V1 Class 2 (MSAC2) chan-
nel to the Option Board. Please consult the documentation of your PROFIBUS
master on how to achieve this.
The Option Board only supports one DP-V1 Class 2 (MSAC2) channel. It is
therefore advisable to close the channel when you are done. Not doing so will
block other users of the parameter channel. Consult the documentation of
your PROFIBUS master on how to achieve this.
The following illustration demonstrates the DP-V1 read/write sequence.
instruction(s)
Instruction(s)
1. The PROFIBUS master generates an MSAC2_Write request with param-
eter instructions. The write instructs the Option Board to either read or
change a number of parameters.
2. If the MSAC2_Write request is valid, the Option Board responds with a
positive write response but no data. If the MSAC2_Write request is invalid,
the Option Board responds with a DP error.
3. The Option Board starts processing and executing the parameter instruc-
tions:
• While the Option Board is processing read instructions, it fills the result
data with parameter values. If the Option Board encounters an error,
the corresponding value is replaced with a PROFIdrive error number
(Refer to section E-5 Parameter Value Formats).
• While the Option Board is processing change instructions, it generally
does not generate result data. However, if it encounters and error the
result data is filled with either zero-data (no error) or the corresponding
error value and element index (Refer to section E-5 Parameter Value
Formats).
4. The master polls the Option Board with an MSAC2_Read request.
5. While the Option Board is busy executing the instructions, it responds with
a negative read response (state conflict).
6. Once the Option Board is finished with the parameter instructions and the
result is available, it responds with a positive read response, and the in-
struction result + data.
Note Consult the documentation of your PROFIBUS master to obtain information
on how the above sequence may be automated.
Master DP-V1 Class 2
communication channel
Parameter MSAC2_Write request
Parameter instruction(s)
MSAC2_Write response
(no data)
MSAC2_Read request
(no data)
MSAC2_Read response
state conflict (no data)
MSAC2_Read request
(no data)
MSAC2_Read response
result Instruction(s) result
Section 4-5
Option Board
*1
*2
*4 *3
Processing
instructions
*5
*4
*6