Chapter 6 Applied Instructions 
6-509 
4.  When the UDP connection is started, if the number of servers which can be connected 
reaches the upper limit, or there has been a connection, the error occurs, the corresponding 
error flag is ON, the error code is 16#600B, and the instruction is not executed. 
5.  When the AH500 series PLC is the client and the TCP connection is started, if the local 
communication port has been used, the error occurs, the corresponding error flag is ON, the 
error code is 16#600C, and the instruction is not executed. When the AH500 series PLC is the 
client and the TCP connection is started, if the local communication port number is 0, the error 
occurs, the corresponding error flag is ON, the error code is 16#6201, and the instruction is not 
executed. 
6.  When the UDP connection is started, if the local communication port has been used, the error 
occurs, the corresponding error flag is ON, the error code is 16#600C, and the instruction is 
not executed. 
7.  When the TCP connection is started, if the value in the high word of the remote IP address is 0, 
127, or the value larger than 223, the error occurs, the corresponding error flag is ON, the error 
code is 16#6200, and the instruction is not executed. 
8.  When the UDP connection is started, if the value in the high word of the remote IP address is 0, 
127, or the value larger than 223, the error occurs, and the corresponding error flag is ON, the 
error code is 16#6209, and the instruction is not executed. 
9.  When the UPD connection is started, if the local communication port number and the remote 
communication port number are 0, the error occurs, the corresponding error flag is ON, the 
error code is 16#620A, and the instruction is not executed. 
10.  When the TCP connection is started, if the socket has been connected or is been connected, 
the error occurs, the corresponding error flag is ON, the error code is 16#6217, and the 
instruction is not executed. When the TCP connection is started, if the socket is being closed, 
the error occurs, the corresponding error flag is ON, the error code is 116#621A, and the 
instruction is not executed. 
11.  During the connection, if the computer as the client abandons the connection, the error occurs, 
the corresponding error flag is ON, and the error code is 16#6214. During the connection, if 
there is a response timeout, the error occurs, the corresponding error flag is ON, and the error 
code is 16#6212. 
12.  When the master and slave all use the AH series PLC, and share the same timeout values; if 
there is a connection timeout for the slave first, the salve will cut the connection. But if there is 
a connection timeout for the master first, the master will send out an error flag and cut its 
connection.