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IC-KP2-2HB21-2V1D
Commands
Master update bit:
As soon as a new command is to be sent to the slave, the following instruction
must be executed:
Write command to the OUTPUT data field:
OUTPUT[1..x] := new telegram
IF (UM_OUTPUT <> UM_INPUT) then (* check whether the slave can receive
new data *)
UM_OUTPUT := UM_INPUT (* slave is ready to receive, transfer of update bit *)
End_IF
On our website www.pepperl-fuchs.com, you will find an example program in
structured text for a Beckhoff controller.
7.2.2
Command Information
Commands and data are exchanged between the PLC and the control interface
using the control byte. For a description of the transfer procedure see chapter
7.2.1.
A command consists of the command code, a specified number of parameters,
and the data relating to the command. The command is entered in the output data
field of the master.
A response consists of the echo of the command code, a parameter, the status, a
reply counter, and the read data. The response is entered in the input data field of
the master.
Some commands do not use all parameter and data fields. The device ignores the
data fields not used.
Once commands have been processed by the identification system, the "Status"
is output in accordance with the Status/fault signal table. (see chapter 7.2.9)
As a response to a read command, the read/write tag sends the status 0 and the
number of (useful) data of the response telegram in the "word count" response
parameter. The word count in a response to a write command is 0 because the
response only contains the status and no (useful) data. Here, the second byte of
the response is not the same as the second byte of the command call-up. With
read only code commands, the word count in the response is always 0.
New commands may only be issued to the device once the response was
retrieved from the previously-issued command.
Enhanced commands are executed repeatedly until a new command is sent on
the same channel.
When the system is switched on, the value on the reply counter is also 0. This
value is incremented every time the response data field is modified.
In the event of an overrun, the counter skips from FF
26
to 01
.
h
h
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