Advantech EKI-1526/N/I/TI, Руководство пользователя

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EKI-1526(TI) | 1528(TI) User Manual 44
The EKI-1526(TI) | 1528(TI) provide Multi-access function through an Ethernet
connection path, allowing a maximum of five connections to open one serial port
simultaneously. In this mode, all connections use the same serial setting. If one serial
setting within this configuration is configured differently, the data communication will
not function correctly.
Figure 4.2 Configuring Virtual COM Mode
The Host Idle Timeout setting monitors the connection between the host and the
device. If the Host Idle Timeout setting time is reached, the device server will release
the resources allocated to the port mapping. This prevents a stalled host from
affecting the connective device.
The Multi-access function has two modes. One is
Normal mode
and the other is
Round-Robin mode
.
4.2.1 Normal mode
By disabling the Response Timeout parameter, the EKI-1526(TI) | 1528(TI) Series
will operate in normal mode. When multiple hosts simultaneously open the serial
port, only the first connected host has management control; the remaining
connections only have a data communication function. Each serial port supports up
to five simultaneous connections, so multiple hosts can transmit/receive data to/from
the same serial port simultaneously. Every host can transmit data to the same serial
port, and the EKI-1526(TI) | 1528(TI) Series will also transmit data to every hosts.
When the multiple hosts transmit data to the same serial port at the same time, the
received data from Ethernet and the outputs of serial port are mixed. When the EKI-
1526(TI) | 1528(TI) Series receives data from serial port, the data will also be
transmitted to the connected hosts simultaneously.
4.2.2 Round-Robin mode
By enabling the
Response Timeout
parameter, the EKI-1526(TI) | 1528(TI) Series
operates in “Round-Robin mode”. Each serial port supports up to five simultaneous
connections allowing hosts to simultaneously transmit/receive data to/from the same
serial port. Every host can simultaneously transmit data to the same serial port, EKI-
1526(TI) | 1528(TI) Series processes the data in the order arrived. The EKI-1526(TI)
| 1528(TI) Series processes the first host’s request and replies. The serial device
server determines the end of the serial acknowledgement through a response
timeout. When EKI-1526(TI) | 1528(TI) serial device server does not receive a
response from the serial port after a response timeout query, the device replies with
an acknowledgement and then processes the next host request.
With an increased number of hosts, response time may be lengthy, increasing the
period of the Response Timeout.
Frame Break
is therefore an important parameter
for Round Robin mode. The parameter is a smart method of reducing ineffective
waiting periods and streamlining the transmission process.