390
Serial Communications Section 6-3
Procedure
Host Link Commands The following table lists the host link commands. Refer to the 
SYSMAC
CS/CJ-series Communications Commands Reference Manual
 (W342) for
more details.
Set the PLC Setup from the CX-
Programmer.
(Set the communications mode to 
Host Link
 and set the parameters.)
Power OFF
Connect the CPU Unit and external device 
via RS-232C. (Mount the RS-232C Option 
Board in option slot 1 or 2.)
Set the DIP switch on the front of 
the CPU Unit.
Turn pin 4 OFF when suing serial port 1.
Turn pin 5 OFF when suing serial port 2.
Power ON
Host computer to PLC
PLC to Host computer
Send Host Link 
commands from 
the host computer.
Send FINS 
commands from 
the host computer.
Execute SEND/RECV/CMND 
instructions in the PLC’s program.
Return a response from the host 
computer. (A program is required in 
the host computer.)
Type Header 
code
Name Function
I/O mem-
ory read 
commands
RR CIO AREA READ Reads the contents of the specified number of CIO Area words starting from 
the specified word.
RL LINK AREA READ Reads the contents of the specified number of Link Area words starting from 
the specified word.
RH HR AREA READ Reads the contents of the specified number of Holding Area words starting 
from the specified word.
RC PV READ Reads the contents of the specified number of timer/counter PVs (present 
values) starting from the specified timer/counter.
RG T/C STATUS READ Reads the status of the Completion Flags of the specified number of tim-
ers/counters starting from the specified timer/counter.
RD DM AREA READ Reads the contents of the specified number of DM Area words starting from 
the specified word.
RJ AR AREA READ Reads the contents of the specified number of Auxiliary Area words starting 
from the specified word.