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Appendix
CASE 2
Inverter State
Not Busy
Com Msg
Legend:
G.
Inverter ready, Command Message 1 received, inverter begins
executing Command 1 and enters busy mode.
H.
Inverter completes execution of Command 1 and exits busy mode.
I.
Command
Command 2 and enters busy mode.
J.
Inverter in busy mode, Command Message 3 received and buffered
by FR-A5NP module.
K.
Inverter in busy mode, Command Message 4 received and buffered
by FR-A5NP module. Command Message 3 is overwritten and,
therefore, lost.
L.
Inverter completes execution of Command 2 and exits busy mode.
M.
Inverter 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 "Inverter Ready / Busy" message built into the FR-A5NP
PROFIBUS-DP option module. Communication coordination is accomplished
using a "Inverter 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 inverter commands are not sent
while this signal indicates that the inverter is in busy mode.
The length of time the inverter 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 inverter.
The inverter's communication state can be determined by reading PKE word.
PKE-AK (PROFIBUS-DP Word 1, bits 12-15) will contain status data as
described below:
PKE-AK
(Word 1, Bits 12-15)
VALUE
0h
1h
7h
Busy
G
Message
2
received,
INVERTER
COMMUNICATION
STATE
Inverter Busy
Inverter Ready
Command Error
52
H
J
K
L
inverter
begins executing
NOTES
Inverter is executing a previous
command and is unable to accept
additional commands and/or data.
Inverter is prepared to receive data.
Inverter received invalid command.
May be due to command syntax error
or communication handshaking error.
M
N
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