Beckhoff TX1200, Руководство пользователя

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Function blocks
TX1200 9 Version: 1.0
3 Function blocks
3.1 FB_ModbusTcpOpen
The function block opens a TCP/IP connection to a remote partner on the MODBUS/TCP port. To keep
resource consumption to a minimum, the maximum number of open connections has been limited to 4. If it is
necessary to establish a further connection, a connection that is not currently in use can first be closed using
the
FB_ModbusTcpClose [
}
10] function block. If successful, the FB_ModbusTcpOpen function block
supplies a port number in the iMyPortNo output variable. This port number is required in order to send a
MODBUS request using either of the FB_ModbusTcpRequest [
}
12] or FB_ModbusTcpClose [
}
10] function
blocks, e.g. to close the connection. When opening the connection, the tTimeout input parameter is also
used to specify the time-out period for the MODBUS request and for the disconnection. After about 10
seconds, a connection that has been opened but has not been used during that period is automatically
closed, and must be reopened if needed.
VAR_INPUT
VAR_INPUT
bStart : BOOL;
sRemoteIPAddr: STRING(15);
tTimeOut : TIME;
END_VAR
bStart : the function block is activated by a rising edge at this input.
sRemoteIPAddr : this variable is a string containing the network address (IP address) of the remote partner.
tTimeOut : indicates the time, which must not be exceeded during command execution.
VAR_OUTPUT
VAR_OUTPUT
bBusy : BOOL;
bError : BOOL;
iErrorId : WORD;
iMyPortNo : WORD;
END_VAR
bBusy : if the function block is activated, this output is set. It remains set until a feedback is received.
bError : if an error should occur during the execution of the command, then this output is set, after the bBusy
output has been reset.
iErrorId : supplies the command-specific error code (table) or the device-specific error code [
}
14] if the
bError output is set.
iMyPortNo : when successful, the port number associated with the connection is returned at this output. The
port number is a dynamic number, generated afresh each time the connection is established.
Error Codes Description
0x8500 Resource error
0x8501 No socket available
0x8502 Open connection error