FR-A5NP Profibus DP
Communications Option Unit
59
E. VFD completes execution of Command 2 and exits busy mode.
F. VFD accepts buffered Command 3, begins execution and enters busy
mode.
Case 2
G. VFD ready, Command Message 1 received, VFD begins executing Com-
mand 1 and enters busy mode.
H. VFD completes execution of Command 1 and exits busy mode.
I. Command Message 2 received, VFD begins executing Command 2 and
enters busy mode.
J. VFD in busy mode, Command Message 3 received and buffered by FR-
A5NP module.
K. VFD in busy mode, Command Message 4 received and buffered by FR-
A5NP module. Command Message 3 is overwritten and, therefore, lost.
L. VFD completes execution of Command 2 and exits busy mode.
M. VFD accepts buffered Command 4, begins execution and enters busy
mode.
To avoid losing data in this manner, it is recommended that the user take
advantage of the VFD Ready / Busy message built into the FR-A5NP Profibus
DP option module. Communication coordination is accomplished using a
VFD Busy signal available via data word number 1, designated PKE word,
as defined in the Profibus-DP network protocol. The user should design the
process control such that VFD commands are not sent while this signal
indicates that the VFD is in busy mode.
The length of time the VFD remains in busy mode is dependent entirely
upon the amount of time required to completely execute a given command.
This period, therefore, is dependent upon the complexity of the command
sent to the VFD.
The VFDs communication state can be determined by reading PKE word.
PKE-AK (Profibus-DP Word 1, bits 12-15) will contain status data as de-
scribed below:
K
A
-
E
K
P
)
5
1
-
2
1
s
ti
B
,
1
d
r
o
W
(
E
U
L
A
V
N
O
I
T
A
C
I
N
U
M
M
O
C
D
F
V
E
T
A
T
S
S
E
T
O
N
h
0
y
s
u
B
D
F
V
d
n
a
d
n
a
m
m
o
c
s
u
o
i
v
e
r
p
a
g
n
it
u
c
e
x
e
s
i
D
F
V
s
d
n
a
m
m
o
c
l
a
n
o
it
i
d
d
a
t
p
e
c
c
a
o
t
e
l
b
a
n
u
s
i
.
a
t
a
d
r
o
/
d
n
a
h
1
y
d
a
e
R
D
F
V
.
a
t
a
d
e
v
i
e
c
e
r
o
t
d
e
r
a
p
e
r
p
s
i
D
F
V
h
7
r
o
r
r
E
d
n
a
m
m
o
C
e
b
y
a
M
.
d
n
a
m
m
o
c
d
il
a
v
n
i
d
e
v
i
e
c
e
r
D
F
V
r
o
r
o
r
r
e
x
a
t
n
y
s
d
n
a
m
m
o
c
o
t
e
u
d
.r
o
r
r
e
g
n
i
k
a
h
s
d
n
a
h
n
o
it
a
c
i
n
u
m
m
o
c
Summary of Contents for FR-A 500
Page 51: ...FR A5NP Profibus DP Communications Option Unit 51 ...
Page 52: ...52 ...
Page 54: ...54 ...
Page 56: ...56 ...
Page 63: ...FR A5NP Profibus DP Communications Option Unit 63 ...
Page 64: ...64 ...
Page 65: ...FR A5NP Profibus DP Communications Option Unit 65 ...