Rockwell Automation 22-COMM-P PowerFlex Profibus Adapter User Manual
Page 102
D-14
SLC Ladder Logic Examples
Figure D.8 Parameter Accessing Routine
Figure D.8 Parameter Accessing Routine (continued)
This section of the routine is only needed if the application needs to perform Parameter Protocol Reads or Writes to Station 2.
On power-up, initialize the Parameter Protocol routine.
0
S:1
15
First Pass
U
B3:19
0
Par Prot
Messaging
Request
This circuit utilizes the Parameter Protocol. A REQUEST to the Profibus adapter is processed only
and after each RESPONSE from the adapter a zero must be sent and received to 'handshake' before the next
REQUEST/RESPONSE transaction can take place. For example:
Send a param. read request --> Receive a param. read response --> Send a "0" --> Receive a "0" --> [Transaction complete]
If the RESPONSE PCA Word 1 (N10:6) is "0", then a REQUEST can be initiated
.
Elsewhere in the user program these words must be loaded with message data prior to initiating the REQUEST.
N7:10 = RC = the operation to be performed ("1" = Read, "2" = 16-bit Write)
N7:11 = PNU = the parameter number to read or write
N7:12 = Subindex = the DPI port # ("0" = Station 0, "1" = Station 1, "2" = Station 2, "5" = 22-COMM-P, etc.)
N7:13 = PVA #1 (the parameter value (high word)) - only used when writing parameters
N7:14 = PVA #2 (the parameter value (low word)) - only used when writing parameters
The four Parameter Protocol Words set up in the scanner are used to perform the Parameter Protocol:
N20:6 = contains RC (the operation to be performed) and PNU (the parameter number to read or write) combined
N20:7 = Subindex (the DPI port #)
N20:8 = PVA #1 (the parameter value (high word))
N20:9 = PVA #2 (the parameter value (low word))
B3:19/0 is turned ON elsewhere in the program after a REQUEST message (N7:10-14) is loaded. This causes one
Parameter Protocol read or write to occur and B3:19/0 is turned OFF when the transaction is complete.
1
B3:19
0
Par Prot
Messaging
Request
EQU
Equa
Source A
N10:6
0<
Source B
0
0<
EQU
RESPONSE
PCA Word
MOV
Move
Source
N7:11
77<
Dest
N20:6
12304<
MOV
PCA Word
N7:10
0
RC bit 0
L
N20:6
12
PCA Word
RC bit 0
N7:10
1
RC bit 1
L
N20:6
13
PCA Word
RC bit 1
N7:10
2
RC bit 2
L
N20:6
14
PCA Word
RC bit 2
COP
Copy File
Source
#N7:12
Dest
#N20:7
Length
3
COP
IND Word
(Subindex)
once at a time,