APPLIES FOR THE FOLLOWING HATTELAND® PRODUCTS:

Stand-alone Computer:
HT B04xx xxx-xx, HT B04PM MIL-xx

Panel Computers - Series 1
JH 10T08 xxx-xx, JH 15T05 MMC-xx, JH 19T02 MMC-xx

Note: Customized models are ALSO affected by this Service Memo.


OVERVIEW:
During test of unused COM ports (3-6) connected to an active network, a problem with high CPU load was discovered. The problem is related to unhandled interrupts in the driver layers. For all "open" COM ports, the interrupts are handled and this error will therefore not reoccur. 


PROBLEM DESCRIPTION:
- High CPU load when receiving data at any of COM3, COM4, COM5 and COM6 when these
  are configured to RS232/RS422/RS485 mode. 
- The problem occurs when affected COM ports are unused in the software application.


CAUSE:
Interrupts caused by the incoming data is not handled by current COM driver present at the Hatteland Display BSP CD. (Current driver Moschip Nm9845. version:5.0.2183.1) 


SOLUTION:
For Microsoft® Windows XP®, use driver for MSC9845 version 2.0.0.7 or later.
Available at Moschip homepage - http://www.moschip.com/mcs9845_downloads.php 


For further enquiries regarding this Service Memo, please contact Technical Support Division at Hatteland Display.