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4. Operating procedures
Useful functions (RS485 communication function)
2. Data transmission system
Item
Specifications
Communication standard
EIA standard
RS-485 compliant
Synchronization system
Asynchronous system
Communication system
Half-duplex communication
Transmission code
ASCII code
Communication rate
1200
／
2400
／
4800
／
9600BPS
Communication dist.
Max.500m
（
depends on environmental influences
）
Network
Multi-drop system
（
Max. 1:31 stations
）
Signal wire
Two wires: transmission/reception
Stop bit length
1
／
2bits
Data length
7
／
8bits
Parity
None
／
Odd
／
Even
BCC check
Enabled
／
Disabled
Response delay time
0
～
250msec
Communication address
1
～
99 stations
（
Max. 1:31 stations
）
Communication mode select
RO
／
RW
Note
）
Settings indicated in
are the initial settings of the Unit.
3. Transmission control characters
Symbol
Name
Code
Description
STX
Start of text
02H
Indicates the beginning of a text
ETX
End of text
03H
Indicates the end of a text
R
Read
52H
Command to read a request
W
Write
57H
Command to write a request
ACK
Acknowledge Character
06H
Transmission of acknowledgement of proper
reception
NAK
Negative Acknowledge
15H
Transmission of reply of reception error
Note) R
: Read (Command to read settings or measurements)
W : Write (Command to write settings)
R command can be always available for communication in any mode.
W command is available for communication only in the normal mode and its specific
parameters that can be communicated differ depending on the operating status (during
operation). See
“7. List of identifiers/commands”.
4. Transmission control procedures
4.1
Communication procedures
・
The Unit returns
“reply message” in response to a “request message” from a host PC.
Thus, the Unit will never start transmission.
・
The Unit does not make any communication for about four seconds after power on (no reply).
Set some delay before start of communication after power on.