78
22.
RS485
Caution in laying cables
When laying transmission lines for communication in the unit, see to it that
they are not in the proximity of, or parallel to, the power line, high voltage
line, high frequency line, etc. Failure to comply with this caution can cause
malfunction.
Remote host
Use a noise-immune isolation for the remote host like PC, sequencer, etc.
Otherwise, malfunction or failure can result.
This section describes how to set and use RS485.
22.1.
Communication Specifications
22.1.1.
Standard specifications
Two-wire system
Half duplex
Start-stop synchronization system
ASCII code
Transmission distance
1200 m*
Maximum number of connections
32 (including host)
Baud rate
9600/19200/38400 bps
* Maximum cable length is 1200m in the RS-485 standard.
Please check a specification of remote host and an environmental noise if you use the cable
of 30m or more.
22.1.2.
Communication setting
DATA
8 bits
Parity
None
Stopbit
1 bit
* Change over the mode to the receiving state within 20 ms after sending data.
* Set the time-out before receiving data at 150 ms or more.
* After receiving data, send the next data with an interval of 50 ms or more.
22.2.
Setting
22.2.1.
RS485 communication setting “L2”
To use RS485, it is necessary to set communication at “L2”.
Display
Detail
“L1”
Operation on front panel external I/O.
“L2”
Only RS485 is operated.
22.2.2.
Baud rate setting
The table below gives the baud rate settings.
Display
Detail
960
9600 bps
192
19200 bps
384
38400 bps
22.2.3.
Address setting
Address can be set from 01 to 32.
* Note that remote host may be allocated to 00.
* The maximum number of nodes is 32 per line, including the host.
* Settings are validated as and when necessary.
22.2.4.
Setting the checksum collating function
Checksum collating function checks if all the data sent and received have been acquired.
Display
Detail
“o”
Checksum is collated.
“F”
Checksum is not collated.
Summary of Contents for G-Tran ISG1
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