Rockwell Automation 20-COMM-P Profibus Adapter - Manual (Page 76)

6-6 Using Explicit Messaging (Parameter Protocol)
Parameter Protocol Examples
Read Examples
Figure 6.3 Overview Parameter Message Format (Read Request)
Bit 15-12 11 10-0 15-12 11 10-0
Parameter Access
Word 1 (PCA)
RC SPM PNU RC SPM PNU
Parameter Access
Word 2 (IND)
Subindex Subindex
Parameter Access
Word 3 (PVA)
Not Used Parameter value high
(32 bit high word)
Parameter Access
Word 4 (PVA)
Not Used Parameter value low
(32-bit low word/ or
8-bit/16-bit value)
Request
Response
Request Response
RC
Set to “1” (‘0001’) binary to read RC
“1” (‘0001’) Transferring 8-bit or 16-bit
parameter value
“2” (‘0010’) Transferring a 32-bit
parameter value
“7” (‘0111’) Request rejected (including fault
code)
SPM
Not used SPM
Not used
PNU
Parameter number to read PNU
Confirms the Parameter number (if
successful, equals the PNU from the
request)
Subindex
Selects which DPI port to talk to (“0” = DPI
Host, “5” =20-COMM-P on PowerFlex 70 Subindex
Confirms the DPI port (if successful, equals
the Subindex from the request)
Not Used Parameter value high word
Contains a “0” if returning a value from a
16-bit parameter and the high word from a
32-bit parameter
Not Used Parameter value low word
Contains the value from a 8-bit or 16-bit
parameter, the low word if reading from a
32-bit parameter, or the fault code (if RC =
“7”)
20COMM-UM006A-EN-P.book Page 6 Friday, September 28, 2001 10:43 AM