8 mrv – GE Industrial Solutions AF-600 FP Profibus DP User Manual
Page 54
5.3.8 MRV
Speed reference, the data format is "Standardized value". 0 Hex = 0% and
4000 Hex = 100%.
In the example, 2000 Hex is used, corresponding to 50% of maximum fre-
quency (par. F-53 Maximum Reference).
The whole PPO therefore has the following values in Hex:
Byte
Value
PCV
PCA
1
31
PCA
2
55
IND
3
00
IND
4
00
PVA
5
00
PVA
6
00
PVA
7
03
PVA
8
E8
PCD
CTW
9
04
CTW
10
7F
MRV
11
20
MVR
12
00
The process data within the PCD part acts immediately upon the frequency
converter, and can be updated from the master as quickly as possible. The
PCV part is a "handshake" procedure which means that the frequency con-
verter has to acknowledge the command, before a new one can be written.
A positive response to the above example may look like this:
Byte
Value
PCV
PCA
1
21
PCA
2
55
IND
3
00
IND
4
00
PVA
5
00
PVA
6
00
PVA
7
03
PVA
8
E8
PCD
STW
9
0F
STW
10
07
MAV
11
20
MAR
12
00
The PCD part responds according to the state and parameterisation of the frequency converter.
The PCV part responds as:
- PCA: As the request message, but here the RC part is taken from the response table, see the PCA handling section. In this example RC is 2 Hex, which is a
confirmation that a parameter value of the type long word (32 bit) has been transferred. IND is not used in this example.
- PVA: 03E8Hex in the PVA part tells that the value of par. F-07 Accel Time 1 is 1000, which corresponds to 10.00.
- STW: 0F07 Hex means that the motor is running and there are no warnings or faults (for details see the Status word table in the Status word section).
- MAV: 2000 Hex indicates that the output frequency is 50% of the maximum reference.
A negative response may look like this:
Byte
Value
PCV
PCA
1
70
PCA
2
00
IND
3
00
IND
4
00
PVA
5
00
PVA
6
00
PVA
7
00
PVA
8
02
PCD
STW
9
0F
STW
10
07
MAV
11
20
MAR
12
00
RC is 7 Hex, which means that the request has been rejected, and the fault number can be found in the PVA part. In this case the fault number is 2, which means
that the upper or lower limit of the parameter is exceeded. See the fault number table in the PCA handling section.
AF-650 GP/AF-600 FP Profibus DP Operating Instructions
53
5