Onboard Variables in PCI 7344

[Giridhar_Rajan]

Hi,

I am trying to use the 120 onboard storage locations provided PCI 7344 motion controller. Firstly, i'm not able to store floating point values in it. If I try to store 25.234, it takes in only takes 25. I have somehow overcome the problem by multiplying my number by 1000 while storing and dividing by 1000 after retreiving it, so that the decimal value vanishes while storage. I would like to know if there is any other way. Secondly, the card is able to remember the values only till my PC in ON. The data is lost once the PC is restarted. Please suggest a solution for this.

Regards,

Giridhar Rajan

Automation Engineer, Design

Cruiser Controls

Mumbai, India

[Jochen]

Giridhar,

all the calculations on the 7344 are done in fixed point integer arethmetic (DSPs and FPGAs typically don't support floating point numbers). That's why onboard variables can only store integer values.
Onboard variables reside in the board's RAM so the values get lost when the PC is turned off. If you need these values even after a restart of your PC you will have to store the values to non-volatile memory before turning off the PC and load them again to the onboard variables after a restart. You could either store the values on your computer's harddrive or in the ROM of your 7344 by using the Object Memory Managment function. For the latter option you will have to write the onboard variables to a buffer first and then store the buffer to the ROM.

I hope this helps,

Jochen Klier
National Instruments Germany

[Giridhar_Rajan]

Hi Jochen,

Thanks for the help. I sure it should work using buffers.

Regards,

Giridhar Rajan

Automation Engineer

Cruiser Controls

Mumbai, India