YOKOGAWA F3LC11-1F, User Manual

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A2-4
IM 34M6H41-02E 2nd Edition : Aug. 1, 2005-00
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Character Length, Parity Bit, Stop Bits, Ending Character
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Character Length
In serial communications (RS-232-C, RS-422/485), a single character data (1 byte) is
transmitted as 7 or 8 bits. This is known as the character length. PC link commands of
this module use only ASCII codes within the range of $00-$7F and hence can accept
both 7-bit and 8-bit lengths. However, event transmission function and message
transmission function may contain 8-bit transmission data, and hence should only be
used with 8-bit length.
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Parity Bit
The parity bit is used to detect error within a single character. When you enable the
parity bit (odd parity or even parity), single bit change (0
→
1 or 1
→
0) in the data due to
noise, etc. can be detected.
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Stop Bit
The stop bit is appended to data for each character (if there is a parity bit, it is appended
behind the parity bit) and is used for character data synchronization
(Start-Stop synchronization). 1 stop bit is normally sufficient but if the remote equipment
is prone to communications error, 2 stop bits are recommended.
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Ending Character
The ending character is appended to the character string of a PC link command or the
character string of a response to a PC link command and is used for end identification.
The last character of the character string of PC link commands and responses is the
ETX ($03) character. If the ETX character is used to identify the end of the character
string, it is not necessary to append an ending character. However, some displays and
BASIC language, etc. uses CR (or CR+LF) for end identification. When connecting to
these types of higher-level equipment, you should set the ending character to “Yes”.
Append an ending character when connecting to TOP series from Yokogawa.