Moxa Technologies 5110 Series user manual TCP Server Mode, TCP Client Mode

NPort 5110 Series User’s Manual Choosing the Proper Operation Mode

Overview

NPort 5110 Serial Device Servers are used to network-enable traditional RS-232 devices. A Serial Device Server is a tiny computer equipped with a CPU, real-time OS, and TCP/IP protocols that can bi-directionally transfer data between the serial and Ethernet formats. Your computer can access, manage, and configure remote facilities and equipment over the Internet from anywhere in the world.

Traditional SCADA and data collection systems rely on serial ports (RS-232) to collect data from various kinds of instruments. Since NPort 5110 Serial Device Servers network-enable instruments equipped with an RS-232 communication port, your SCADA and data collection system will be able to access all instruments connected to a standard TCP/IP network, regardless of whether the devices are used locally or at a remote site.

NPort 5110 is an external IP-based network device that allows you to expand the number of serial ports for a host computer on demand. As long as your host computer supports the TCP/IP protocol, you won’t be limited by the host computer’s bus limitation (such as ISA or PCI), or lack of drivers for various operating systems.

In addition to providing socket access, NPort 5110 also comes with a Real COM/TTY driver that transmits all serial signals intact. This means that your existing COM/TTY-based software can be preserved, without needing to invest in additional software.

Three different Socket Modes are available: TCP Server, TCP Client, and UDP Server/Client. The main difference between the TCP and UDP protocols is that TCP guarantees delivery of data by requiring the recipient to send an acknowledgement to the sender. UDP does not require this type of verification, making it possible to offer speedier delivery. UDP also allows data to be unicast or multicast to only one IP or to different groups of IP addresses.

TCP Server Mode

In TCP Server mode, NPort 5110 is configured with a unique IP:Port address on a TCP/IP network. NPort 5110 waits passively to be contacted by the host computer, allowing the host computer to establish a connection with and get data from the serial device. This operation mode also supports up to 4 simultaneous connections, so that multiple hosts can collect data from the same serial device—at the same time.

As illustrated in the figure, data transmission proceeds as follows:

1.The host requests a connection from the NPort 5110 configured for TCP Server Mode.

2.Once the connection is established, data can be transmitted in both directions—from the host to the NPort 5110, and from the NPort 5110 to the host.

TCP Client Mode

In TCP Client mode, NPort 5110 can actively establish a TCP connection to a pre-defined host computer when serial data arrives.

After the data has been transferred, NPort 5110 can automatically disconnect from the host computer by using the TCP alive check time or Inactivity time settings. Refer to Chapter 5 for more details.

Data transmission proceeds as follows:

1.The NPort 5110 configured for TCP Client Mode requests a connection from the host.

2.Once the connection is established, data can be transmitted in both directions—from the host to the NPort 5110, and from the NPort 5110 to the host.

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