To connect a device, the system needs to transfer the device-related connection parameters.
protocol indicates the protocol used for communication. At present, RS485 and TCP can be used.
port: Communication port of the device. For example, if the RS485 protocol is used, you can set port to COM1: If the TCP is used, the default port is 4370 unless otherwise noted.
deviceid: Device ID used by the serial port.
baudrate: Baud rate used for the communication of the communication of the serial port.
ipaddress: IP address of the related device for TCP/IP communication.
timeout: Timeout time of the connection (unit: ms)If the network connection is in poor condition, you should set the parameter to a larger value. Usually, timeout=5000 (5 seconds) can meet the basic network needs. When the query result contains the error code of -2, you should set timeout to a larger value, for example, timeout=20000 (20 seconds).
passwd: Connection password of the communication. If the parameter value is null, it indicates that no password is used.
(Note: The connection parameters are case-sensitive)
[Returned value]
If the device is connected successfully, the connection handle is returned. Otherwise, the error code of 0 is returned.
[Example]
Python:
params = “protocol=TCP,ipaddress=192.168.12.154,port=4370,timeout=4000,passwd=”
self.commpro = windll.LoadLibrary("plcommpro.dll")		
constr = create_string_buffer(params)
self.hcommpro = self.commpro.Connect(constr)
c#:
params = “protocol=TCP,ipaddress=192.168.12.154,port=4370,timeout=2000,passwd=” ;
IntPtr h = Connect(params);