I have experienced the same timeout issues.
If you are using the MODBUS TCP/IP driver for the PLC there is a menu button "Settings..." that takes you to the "IP Address Settings" window and there is a "Timeout (sec): " pull down menu to set the TCP/IP timeout. I'd try changing this to 3 seconds.
If you are using the TRI_FX driver for the PLC there is the same "Setting..." menu.
If you are using the TRI_FX driver and need to access DM32[] you should download the most recent version of EasyBuilder Pro V5.02.01 Build 2015.08.06 from KEP at:
http://brian.kep.com/EBproV50201_20150806.zipThis version includes a fixed driver for the Fx series PLC. If you switch to an FMD series PLC and need access to DM32[] the driver has not been fixed and I suggest that you use Modbus TCP/IP or Modbus RTU as these drivers have the option of fixing the word order when accessing multiple DM[] registers to get the full 32-bits of a single DM32[].
Because of the timeout issues with the communication between the HMI and PLC, I decided to only use the TCP/IP drivers for debug. For production I run a serial cable between the HMI and PLC and switch the driver interface back to RS232 or RS485 and have no problems with timeouts or lost data.
Gary D*ickinson