serial port overrun

The Dell downloads show an Intel Serial I/O driver.  Its not clear if this is the hardware device for the RS232C I/O or not, but if it is its a later driver than the default Windows driver.  The 2006 date on the Microsoft driver is a generic date, there are several devices that have similar old dates. e.g. the Microsoft Firewire driver that I use on my recording studio system also has a 2006 date but its the "latest" driver. 

<ADMIN NOTE: Broken link has been removed from this post by Dell>

By the way, the "Workstation" section of the forum is for Precision hardware support.

Try enabling hardware flow-control.

Check protocol settings match on both ends.

Use high-quality cables.

Hi,

I have exactly the same problem with my Dell Precision 3630 Tower serial port.
I also run Windows 10 Enterprise 64bit (1809)
Dell Support changed the mainboard but this does not help.
It seems to be a driver problem.

I installed the actual "Intel-Serial-IO-Driver_RDY6W_WIN_30.100.2020.7_A05.EXE" driver.
Nevertheless, the serial port shows driver version "21.06.2006, 10.0.17763.1" from Microsoft and not an Intel or Dell driver.

We bought an active "ProSupport Plus" with the workstation, but after changing the mainboard, the Dell Support blocks further attempts to fix this problem.
This is not what I understand as professional support.

Remark: I use the same cable and serial devices at the Dell Workstation what I had used since some years with my old HP 440 Workstation without any problems.

Best Regards
Andreas

The driver you posted is for specific intel chipsets not a generic serial driver.

Cannon Point-LP Serial IO SPI Controller

This package contains the Intel Serial IO driver and is supported on Alienware, Inspiron, Latitude, OptiPlex, Precision, Vostro, and XPS models that run the Windows 10 64-bit operating system.

https://dl.dell.com/FOLDER05014305M/4/Chipset_Driver_C67R4_WN32_30.100.1727.1_A01_01.EXE

PCI\VEN_8086&DEV_9DAA Serial IO SPI Controller

PCI\VEN_8086&DEV_9DAB
PCI\VEN_8086&DEV_9DFB

PCI\VEN_8086&DEV_A32A  Intel Management Engine Interface SOL
PCI\VEN_8086&DEV_A32B
PCI\VEN_8086&DEV_A37B

> Those ports are not designed to run 115200 baud RS232.

Baloney.  I had no problem running com ports at 115k  20+ years ago with a 386. 

Overruns normally happen when some process disables interrupts too long, and it is almost always a software issue.

One standard way to remedy is to change the trigger levels for the receive and transmit buffers as per below image.  (Win 7)

 

 

Another possible remedy would be to install a serial port card that has a deeper FIFO than on the onboard serial port [16550 (?) with 16 bytes] like the 16950.

Chipset: Oxford OxPCIe952.
Compliant with PCI Express Base Specification, Revision 1.1.
Built-in 128-byte FIFO buffers.
UART: 16950.
Supports data transfer rate up to 230Kb/s.

 

Not going to agree with this statement.

Every single pc I always had , had 0 issues going at 115k on serial, including workstations.

Now if you mean that fujitsu, supermicro, old AST, asus , etc are all wrong in the standard implementation and dell is right, I'm going to not agree

115200 is possible but with zero errors is not especially in a noisy environment over long distances.

Intel AMT Serial-over-LAN (SOL) is something completely different.

This is also why I recommend RS422

RS422 interface is used to transmit data at higher speed and for larger distance compared to RS232C. This is possible due to differential mode of transmission. It uses twisted pair cable for transmission CAT5. Hence noise is reduced to great extent.

https://www.amazon.com/Serial-Converter-Adapter-Supports-Windows/dp/B0195ZD3P4

https://www.amazon.com/USR-TCP232-306-Serial-Ethernet-Device-Server/dp/B07G5P4CPR

If you need flow control and Modbus thats more expensive.

https://www.icselect.com/vxi-11_modbus_RTU.html

@speedstep

I do not use a long cable, I use a 2 meter (6.56 ft) cable, and as I wrote previously, exactly the same configuration run without problems for years with a HP 440 workstation serial port and Win7 Pro 64.

Then try installing an add-in serial port card that has a much deeper FIFO than the standard 16550 -- such as the 16650, 16750, 16850, 16950 or 161050 UART.

@JSz 

JSz, thank you for the tip with this Fifo setting!

After I exactly used your recommended setting and after a reboot, it seems that the serial port now is handled error free, so no characters are missing.

I will watch the serial ports behaviour the next days, if there are still some characters missing, I will buy a serial add-in card with a better UART.

If you still have errors, you can try to set the trigger level for the receive buffer to 4

The explanation behind this is that:
with (14), 3 more characters will overrun the FIFO
with (8), 9 more chars will be needed for overrun
and with (4) 13 more chars will be needed to overrun the UART's FIFO (assuming a standard 16550)

The lower trigger numbers result in higher interrupt frequencies, but the chance of overrun can lessen very significantly.   Methinks the default should be 8, not 14, but I'm not in charge of setting that.

With the higher numbered UARTs the buffer can be as large as 128 - 256 bytes, which is a heck of a lot more than the standard 16.

JSz, Thank you again for the explanation!
It is always helpful to know the technical background.