2 com port problem.

[BigDaz]

Hello,

I have 2 RS422 ports on my PC that are each capable of 3 MBaud. These are all installed ok according to Device Manager. They both work individually but when using them at the same time, at quite a high data rate, the ports just lock up and nothing can get in or out.
Could this be a windows problem?

Cheers, Bigdaz.

 

[micker377]

Are these ports part of the mobo, or an add-on board? What OS?

 

[Frank4d]

I am using two asynchronous RS-485 ports on a computer at work, each 1.5Mbps. I haven't had problems yet but have read in the user's manual that you can have problems if the Page Table Entries (PTE) setting in the registry isn't set high enough.

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management]

Another card that I am using is a 2Gbps serial card and recommends a setting of 20000 to 100000 (decimal) although I haven't seen a problem yet. They claim if the setting is too low, Windows may fail to access the card properly. For most systems the default assigned by Windows is 0.

Again, I haven't seen a problem (no application software yet)... I have only read about it.

 

[BigDaz]

Yeah sorry about that; It's on a Windows XP machine with SP1 and on one with SP2.

I have a 2 port 18MBaud brainboxes RS422 card, also i have 2 Altronix USB to RS422 adapters and a piece of software that has 2 virtual com ports.

The problem is that using 1 port works fine most of the time but when i try and use 2 ports both just lock up, which ever combination that i try. They are all set to 2MBaud.

I looked for Page Tables Entries in the registry but couldn't find it.

cheers, BigDaz.