Applies To:
  • CitectSCADA 5.xx
  • CitectHMI 5.xx

HITACHI driver fails to establish communications with H200 and H700 via TCP/IP. The driver is able to successfully perform an Initialise Unit, but subsequent requests are ignored, and #COM is displayed on the screen.

The syslog.dat file trace looks something like this:

Wed May 17 10:22:01 2006 60:29:38.113 Error: Unit not responding
READ 0007 port1 device1 WR0000C 1
Generic 000007 Driver 00000021 (0x00000015)

Wed May 17 10:22:09 2006 60:29:45.614 Error: Channel offline, cannot talk
READ 0015 port1 device1 WR0000C 1
Generic 000021 Driver 00000020 (0x00000014)

The new models of the Hitachi PLC range use a new command code A0 - A5.  While the older Hitachi PLC range use command code 40-45.
By default the Citect Hitachi driver uses command code 40-45. To force the driver to use the newer command codes, use the following Citect.ini parameter:


Communications should now work using this parameter.

Hitachi, TCPIP, H200, H700