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3 Questions for your AD5700-1

Question asked by Kaos on Sep 14, 2015
Latest reply on Oct 28, 2015 by Kaos

Dear Sir/Madam,

 

Our customer is verifying with your AD5700-1.

So I got the following questions.

 

Your datasheet show that there is the RXD Low around 600msec after CD asset on Fig-5.

 

Q-1

Why is RXD drop Low 600msec? Reason why?

Q-2

What is the min-max time RXD Low?(600msec +/-??msec)

Q-3

Is there the case of still High RXD(not drop to Low)?

 

fig-5.JPG

 

Fig-22 on your datasheet also show RXD drop to LOW when the start and the stop during 8bit data+parity.

Is this UART rule?

Min-Max value also?

 

Here is additional comment from our customer.

In the case of Low level time around 600usec on your datasheet Fig-5, AD5700-1 cannot recognize that it is START bit due to less than 833usec+/-1% HART standard.

Custmer think the reason why is that the head is START-bit.

Because RXD signal is effective after assert CD signal, START-bit become short Low time.

Even though HART signal timing is same, Low level time varies much.

Customer caught no-Low-level(still High level).

 

Thanks Kaos

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