ED7124 Excitation issues


In testing a circuit which is an exact copy of  your CN-0376 schematics for RTD, I come across an annoying situation.

Note that in CN-376 Ref1 is used. I use Ref2 and different AIN's see software below.

The excitation current drops to 0 after some time. I could set the time with the delay parameter!

I would expect to see a continuous voltage at the IOUT pin of approx 2.5V @ (Rref +Rrtd+Rbias)= 10K Ohm .

Again, if I remove the delay, the circuit does not work because I don't get any excitation.

What is happening here?

Brg Joost

                SPI.transfer(0x01);                              // internal ref enable = 01 ; ref enble  & CS_EN High : 03
                SPI.transfer(WRITE_OPERATION | IO_CONTROL1);     //Exitation                       
                SPI.transfer(0x00);                              //AIN0 Iout0 enable 250 uA; ; Iout 1 off;                                   
                SPI.transfer(WRITE_OPERATION | CH0);
                SPI.transfer(0x81);                             // 80 = enable
                SPI.transfer(0x6A);                             // AIN11+; AIN10-         
                SPI.transfer(WRITE_OPERATION | CONFIG0);        //Ref2; AIN buf on; Ref buf on; bipolair
                SPI.transfer(0x09);                             // 09E8 =Ref2, all buf's on
                SPI.transfer(0xE8);                             //PGA =1               
                delay (10000);