Advantech EKI-1352, EKI-1351 manual Multi-Access Mode Shared COM port mode

2.1.2.2Multi-Access Mode (Shared COM port mode)

Most of serial devices are connected directly and physically to the PC serial ports via a cable. The operation system, ex. Windows XP, provides the COM ports that user’s application can access, and control the serial device through the serial cable. This means that the serial device can be connected to one host and only one application on this host can handle input, output and control operation on this device.

If you want to run more than one applications to use a serial device, you can employ EKI serial device servers that provide a virtual COM port for a host or multi-hosts on an Ethernet network. EKI serial device server is located between hosts and serial devices. Each serial port on the EKI serial device server can allow max. of five host connections through 802.11b or 802.11g WLAN. There are two major operation modes for Multi-Access Mode. First one is broadcast mode; EKI serial device server handles a command from one application and replies the data from the serial port to all applications that are connecting this serial port. Another one is polling mode; EKI serial device server handles the command from one application and reply to this application only. Query from other applications must be queued and wait for current process completing.

Figure 2.3 Multi-Access Mode

By using a serial derive server to share serial device, you eliminate the separate serial lines and serial devices that can be attached to individual hosts. Collecting the data from these serial devices become more easily and more effectively.

EKI-1351/1352 User Manual 8