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NDA-24233 Issue 2 Page 1-5
VisuaLink 128/384 Engineering Guide Chapter 1
1.5 Communication Procedure
There is no procedure for communication between a console and VisuaLink as a rule. Therefore, a
communication line is presumed to be error-free. When it is remotely operated with a modem, efficient
operation may not be expected when a line error occurs. Because of this, in a remote control, a modem with
error correction feature shall be used, or VisuaLink shall be checked for operation.
Command/Response Procedure
VisuaLink transmits a confirmation on whether a command is received and the process is completed. After
sending a command, please always analyze the transmitted response before issuing a next command. If the
next command is issued before a response, an error response such as ''currently processing'' may be returned.
(1) Command 1 is issued using the external control port rather than a personal computer.
(2) Analysis of a received command (parameter error, etc.) is implemented.
(3) After an analysis, if it is normal, a normal response is transmitted to a personal computer after
transmitting to the remote in communication. However, if it is error response, the error shall be
analyzed, and a command shall be either suspended or re-issued.
(4) After verifying that Response 1 is normal, issue Command 2.
Note:
After issuing a command from a console, if an alarm emits in VisuaLink, an alarm report may be
transmitted before a response to the command.
Abnormal Handshake Procedure
When the VisuaLink receives a report command from a remote unit at a time the VisuaLink is sending a
command to the remote unit in communication, the VisuaLink transmits an indication to a PC using the
external control port and then transmits a command to the remote unit.
PC Console VisuaLink
Command 1
Command 2
Response
Response
Console VisuaLink Remote
Command 1
Report Command
Response 1
Command 1
Report