Extern

[BeeHay]

Having a tough time enabling my analog output (there are 3 outs) on my lawson labs board...

I did mess with the extern stuff when I initally started DF, but that was sometime ago.

Here is some documentation from their site.

BOOLEAN SendAnalogOut(void)
{ 
// Supported by Model 302 only

BYTE bDAC = 1;
DOUBLE dblVoltage = 2.5;
bCurListIndex = 0;

if(!pSP_SendDAC(pausDevList[bCurListIndex], dlbVoltage, bDAC, bReserved))
{ /* do critical error handling here */ }

// Update controls to reflect new DAC settings 
}

Now I have added this to my device config -

extern("ll_usb2k.dll","ubyte EX_SendDAC(uword, double[1], ubyte)","SendDAC","stdcall","DevID, Output, Channel")

global SendDAC=0

....and have made a button with this quick sequence -

SendDAC(@DevID[0], @double[1], @ubyte, 0, 2.5, 1)

Just trying to get one of the 3 output channels to display 2.5.

Thanks in advance!!

[AzeoTech]

Alas, the snippet you sent from their manual shows a sample of how to call their function from C. I need to see the exact prototype of the EX_SendDAC() function, preferably from the .h header file they provide.

[BeeHay]

Does this help? (you dont have to post this if not needed)

BOOLEAN   SP_SendDAC(USHORT usDevID, DOUBLE dblVoltage, BYTE bDAC, BYTE* pbReserved); 

Arguments 

usDevID: 
16-bit data variable representing the device that you wish to send analog data to. 

dblVoltage: 
Voltage to send to Model-302 

bDAC: 
8-bit data variable that represents the channel to send the analog voltage to 

pbReserved: 
Pointer to an 8-bit data variable. This is currently reserved for future use. 

Return type: 
8-bit. 1 (true) = success,	0 (false) = failed

[AzeoTech]

Yes.

Your extern was wrong. You want (I believe):

extern("ll_usb2k.dll","ubyte SP_SendDAC(uword, double, ubyte, ubyte[1])","SendDAC","stdcall","DevID, Output, Channel")

That should fix it. You have to get the prototype EXACTLY right or you'll likely crash DAQFactory because the stack will get messed up. Your extern only had three parameters, and had the double as a pointer by doing [1]. Only the 4th parameter is a pointer.

[BeeHay]

Awesome as always, thanks!

[BeeHay]

Hmm, thought I had this working, but must have since lost that .ctl file...

Would this be the correct way to send out to my analog out?

SendDac(DevID[0], 1, 0)?

I'm getting "Invalid number of parameters."

Also, would like to get the Digital Out to work.

Would this be the correct way to add it to my device config? -

extern("llusb_2k.dll" "ubyte EX_SendDigout (uword, ubyte)","SendDigOut","stdcall","DevID", Digital Chn Out")

Anything helps!

Thanks!

[AzeoTech]

No, and no I'm afraid. For SendDac, it requires four parameters. Look at the actual prototype. The fourth parameter is reserved, but still has to be passed. Just make a private called junk and pass a pointer to it (@junk)

As for the second one, I don't have the prototype in front of me to compare, but you have some basic errors: 1) you can't have a space after the function name and before the ( in the prototype. 2) you have an extra quote in the 5th parameter of extern. It says "DevID", and should say "DevID,

[BeeHay]

I was wondering what to do with the 4 parameter.

Ahh, now I see why the close ) wasn't turning blue.

:bonk:

The prototype for the second is this -

BOOLEAN SP_SendDigOut(USHORT usDevID, BYTE bDigOut, BYTE* pbReserved);

This call is used to send a digital output value to the device. It can be used anytime once the device has been initialized. Valid digital output values are 0-255.

Arguments

usDevID:

16-bit data variable representing the device that you wish to send the digital output to.

bDigOut:

8-bit data variable that represents the desired digital output.

pbReserved:

Pointer to an 8-bit data variable. This is currently reserved for future use.

Return type:

8-bit. 1 (true) = success, 0 (false) = failed

I need to add the resereved parameter, correct?

When I call this, will this just toggle the digital channel I call to "on/off"?

It says valid ranges are 0-255, how would I tell it say, "200"?

Thanks again!

[AzeoTech]

C doesn't really have optional parameters (unlike C++), so if its in the prototype, you have to use it, even if its just a junk or reserved parameter. Typically you want to pass 0 to reserved parameters, but that's up to the manufacturer. So your prototype is (uword, ubyte, ubyte[1]). I don't know the details of this function, but it either sets a single digital out on/off or a whole bank of 8 by looking at the 8 bits.

[BeeHay]

Thanks again for everything.

Haven't tested it yet, will post back with results.

[BeeHay]

SendDac(DevID[0], 1.9, 0, @junk)

and

SendDigOut(DevID[0], 250, @junk)

work great.

It looks like I need to use a different extern to specify my digital channel out.

Thanks again!