YOKOGAWA F3LC11-1F, Руководство пользователя

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C4-12
IM 34M6H41-01E 3rd Edition : Aug. 1, 2005-00
[5] Precautions for communication
(1) You should include timeout handling on the higher level computer to handle situations
where a response is not returned due to say, an incorrect station number specified
in the command. Send a Reset command to initialize the module during timeout
processing (see Section C6.1).
(2) If this module is used to download a program, then you should not load another
program from another source (FA link, Ladder Diagram Programming Tool M, etc.)
at the same time. Otherwise, the operation is not guaranteed.
(3) Even when writing to a shared device, the value may be immediately overwritten if
another CPU is using the same device .
(4) Do not change the setup switches for the station number, etc. during communication.
(5) If a power failure occurs when a monitoring command is in use, it is necessary to set it
again.
(6) The maximum text length that can be transmitted or received each time by this module
is 512 bytes. However, higher level computers usually cannot receive more than 256
bytes. In such cases, make sure that the size does not exceed 256 bytes by reducing
the number of points to be read.
(7) This module performs communication processing during scanning and scan breaks
for sequence CPU modules. When this module is used, there is a time lag until the
next scanning starts; however, the time required for one scanning operation (scan
time) does not change.
(8) When communicating with multiple stations, once you send a command to one
station, do not send a new command to another station until the response for the first
command has been completely received. Otherwise, operation cannot be
guaranteed.
(9) When connecting an F3LC11-2N (RS-422-A/485 type) module to a higher level
computer (or display), connect them as shown in Figures C3.8 and C3.9 so that the S/
R signal lines cross. Connect Send (S) of the higher level machine to Receive (R) of
this module and connect Send (S) of this module to Receive (R) of the higher level
machine.
(10) The inter-character receiving time of this module is 5 seconds. If a command is
interrupted and the next character is not received within 5 seconds, a time-out error
(error code 44) occurs. However, if an ETX is received during this period, then the
data up to that moment is interpreted and an error is returned because the command
is interrupted. However, if a command is interrupted before receiving the station
number or if there is damage after STX is received, no error is returned. (There is no
response)