Toshiba PROFIBUS-DP PBDP-110 - Manual (Page 30)

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10.3 Parameter Access Procedure
In order to read from a parameter or write to a parameter, 2 control bits are provided
for each drive’s data structure. These bits, labeled Req1 and Req0 in the Action Bits
word, can have the following values:
Req1 Req0 Meaning
0 0........... No action (idle state)
0 1........... Parameter read
1 0........... Parameter write (RAM & EEPROM)
1 1........... Parameter write (RAM only)
Similarly, when a drive responds to a parameter read or write request, 2 status bits
per data structure are provided. These bits, labeled Resp1 and Resp0 in the Action
Bits Response word, can have the following values:
Resp1 Resp0
Meaning
0 0........... No action (idle state acknowledge)
0 1........... Parameter read success acknowledge
1 0........... Parameter write success acknowledge
1 1........... Error indication
Note that the PBDP-110 will respond with Resp1:Resp0 = 1:0 upon a successful
parameter write, regardless of whether the write was to RAM & EEPROM or to RAM
only.
Performing a parameter read or write action from the Profibus master involves the
following process:
1. Send a “no action” code (Req1=0 and Req0=0). Every parameter access must
begin from the idle state. Once this state is sent, the Profibus master must then
wait for the PBDP-110 to respond with an idle state acknowledge (Resp1=0 and
Resp0=0).
2. If the action is to be a data write, set the parameter data in the parameter data
write word. If the action is to be a data read, the parameter data write word value
is irrelevant.
3. Set the parameter register number and action code (Req1 and Req0). For an
explanation of parameter register numbers, refer to section 11.
4. Once the PBDP-110 receives the read or write request, it will begin processing it.
The time required to complete the request depends primarily on the connected
drive’s baud rate setting and internal processing state, but can vary from several
milliseconds to several tens of milliseconds.
5. Once the PBDP-110 has completed the request, it will place its response in the
action bits response, parameter number response, and data / error code
response locations:
• If the request was a read, and the read was performed successfully, this will
be indicated to the master by Resp1:Resp0 changing from 0:0 to 0:1. The
parameter number response will equal the accessed parameter number, and
the resulting data read will be placed in the data / error code response word.