User manual

31 EKI-1521/1522/1524 User Manual
Chapter 3 Configuration
EKI-1521/1522/1524 provides Multi-access function through one Ethernet
connection path or dual Ethernet connection paths. Allow the maximum of five
connections to open one serial port simultaneously. In the mode, all connections
have to use the same serial setting. If one serial setting of these connections is
different from others, the data communication may operate incorrectly.
There are two kinds of Multi-access function. One is Normal mode; another is Round-
Robin mode.
 Normal mode: Disabling “Response Timeout” parameter, EKI-1521/1522/1524
will operate in “normal mode”. When multiple hosts open the serial port
simultaneously, the EKI-1521/1522/1524 only offers control ability to the first
connected host but also provides data communication function for others. 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 EKI-1521/1522/1524 will also
transmit data to every host. But, while multiple hosts transmit data to the same
serial port at almost same time (there still have the order of arrival), the received
data from serial device (this should be required by the first order of arrival) will
be transmitted to the connected hosts simultaneously. This causes hosts
receive incorrect data except the host who has the first order of arrival.
 Round-Robin mode: Enabling “Response Timeout” parameter, the EKI-1521/
1522/1524 will operate in “Round-Robin mode”. 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 simultaneously, but EKI serial device server will process the
data communication in order. EKI-1521/1522/1524 will process the first host’s
request and reply the response to the first host. If EKI serial device server
receives nothing from serial port after a period of time set by user in "Response
Timeout" block, the device server will reply the acknowledgement to the host
and then process the next host’s request. The cycle time will be increased when
you increase either the number of the connected hosts or the value of
"Response Timeout".
 Frame Break is a very import parameter for Round Robin mode. This parameter
is a smart way to reduce inefficient waiting time and EKI-1521/1522/1524 can
transmit data more efficiently. Disabling the Frame Break function, EKI-1521/
1522/1524 will wait for data until "Response Timeout" setting time is reached.
During this period, the commands from hosts will be queued and EKI-1521/
1522/1524 just processes this command. Enabling “Frame Break”, if the serial
port idle is longer than the “Frame Break” period, EKI-1521/ 1522/1524 will
assume the communication is completed and continue the next host’s query.
This is an efficient way to reduce the waiting time and improve the performance.
Note This operating mode is suitable for the one major host send the command
and others hosts just listen the data from serial port. If two of connected hosts
send the command at the same time, it is possible that EKI serial device
server will not handle the command and will response the incorrect data.