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14. Standard RS-485 Communication
14-1. Specifications for standard RS-485 communication
Specification Content
Transmission method Half duplex
Synchro system Start-stop synchronization
Baud rate Select from 1 200 bps, 2 400 bps, 4 800 bps,
9 600 bps, 19 200 bps and 38 400 bps.
Data bit length Select from 7 bit and 8 bit.
Parity bit Select from No parity, even parity or odd parity.
Stop bit Select from 1 bit or 2 bit.
Terminator Select from CR+LF or CR
Transmission data ASCII code
Length of cable About 1 km
Address One is selected among 0 to 31.
The number of connection 32 at maximum.
The standard RS-485 communication and Modbus communication, and optional RS-232C
communication, and RS-422 communication, and RS-485 communications are not interlocked each
other.
14-2. Data format
As for the data format, refer to [6-3-12. Command mode data format].
14-3. Item of standard RS-485 communication setting
14-3-1. Operation mode
The operation mode for standard RS-485 communication is selected by setting function F-47. The
operation mode can be selected from [Command mode], [Stream mode], [Synchronizing with finish],
[Synchronizing with accumulation signal], [Synchronizing with print signal], and [Modbus].
Default is set to [Command mode]. See "15. Modbus communication" for details of Modbus
communication.
(1) Command mode
Data is sent back from CSD-903 to the host side according to the command/data sent to CSD-903
and provided by the host (personal computer or sequencer, etc.).
(2) Stream mode
When RS-485 is used, it keeps outputting the latest data of the output target selected by function
F-47.
Note that the output frequency changes depending on the baud rate setting.
(3) Synchronizing with print signal
Data is output synchronized with the print signal (F key, external control input, or automatic print).
(4) Synchronizing with accumulation signal
Data is output when [Accumulation command] is input by the function F-50 setting, key, or
external control input.
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