RComm::Write()->Not able to write 259 bytes at a time

[nokia_forum_chandru]

Hi,

I am using RComm::Write() to download files to COM POrt. When I try to write 259 butes at a time, it only writes 3 bytes.
But writing 55 bytes was successful.

I had set receive buffer length to 4096bytes
commPort.SetReceiveBufferLength (4096);

Any one had faced this probelm??

Thanks in advance
Chandru

[wizard_hu_]

Can it happen that you use some TUint8 or TInt8 variable and/or do some "& 255" or "& 0xFF" stuff for some reason? Note that 259=256+3.
Post some code snippets.

[nokia_forum_chandru]

Here is code snippet....


RComm commPort;
commPort.Config (portSettings);
portSettings ().iRate = EBps115200;
portSettings ().iParity = EParityNone;
portSettings ().iDataBits = EData8;
portSettings ().iStopBits = EStop1;
portSettings ().iFifo = EFifoEnable;
if (handshakingMode == '2')
portSettings ().iHandshake = (KConfigObeyXoff | KConfigSendXoff); // for xon/xoff
else if (handshakingMode == '1')
portSettings ().iHandshake = (KConfigObeyCTS | KConfigFreeRTS); // for cts/rts
else
portSettings ().iHandshake = KConfigFailDSR; // for no handshaking
..
..
..
commPort.Write(iReadWriteStatus , iActivateInfo , aLen);
User::WaitForRequest (iReadWriteStatus);

aLen = 259 and iActivateInfo is TBuf8<260>

[wizard_hu_]

What is the type of aLen? Is it calculated somehow? How?
Which 3 bytes are transferred? The first 3? The last 3? Something else?

[nokia_forum_chandru]

Hi,

aLen is of type TUint8....
iActivateInfo is TBuf8<260>

aLen = iActivateInfo.Length(); // its value is 259 in my case..

I can not make out... whether it is first 3 or last 3 bytes are written to the port....

Suprisingly
iReadWriteStatus.Int() is equal to 0 after commPort.Write(iReadWriteStatus , iActivateInfo , aLen); is called....

Chandru

[ivey]

Can it happen that you use some TUint8 or TInt8 variable and/or do some "& 255" or "& 0xFF" stuff for some reason? Note that 259=256+3.

This is exactly what is happening :) Make aLen a TInt and it should work

[wizard_hu_]

Thanks Ivey :-)

A slight addition: I am almost sure that the compiler produces a warning about this. (Ok, I acknowledge that there are also some annoying warning messages originating in the SDK, and their lengthy appearance can cover the other messages a bit)

[nokia_forum_chandru]

Thanks a lot .... Its working now...

It was really surprising...... I did not imagine this could be the problem...:))

Thanks any way...