Romilly's HART® and Fieldbus Message Board
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Hart Physical Layer
Message posted by Andrew (andrew.barningham@mht-technology.co.uk : 82.69.1.84) on 10 January 2008 at 10:52:37.
I am using the HT20C15 Hart modem in my hardware. I based the design around the HT2015DS-0303 datasheet.
I can transmit out on the Hart Fieldbus successfully. I can recieve data back on the hart fieldbus O.K. to a degree, i recieve the correct number of characters but 2 or 3 of the characters are incorrect (eg 0x40 is read as 0x80... the 1 bit is in the wrong position)
I found by tweeking the filtering cap and the ICDREF resistor, the characters can change.
My question is.... is there a standard recieve filter circuit for the HT20C15.
Am I using the wrong Hart modem, is there a better hart modem which I could use.
Any advice would be appreciated.
Kind regards
Andrew
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