31
10.3 Parameter Access Procedure
In order to read from a parameter or write to a parameter, two 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:
