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TTL into ACC24E3A Analog Feedback Mezzanine?


JeffLowe
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We have one aux axis that has a TTL encoder. Is it possible to route this into the analog mezzanine on our ACC 24E3A along with the other 3 sine encoders? I understand that it will not be interpolated, but we are only looking for 1/t for this axis and do not want to add another card.

Thanks.

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We use the same differential line receivers on our analog encoder boards as we do on our digital encoder boards, so we can accept digital encoders properly on them. The pullup/down/termination loading is somewhat different, but for an encoder with reasonable drive capability, this should not matter. If it is a single-ended encoder, you will need to tie the "-" inputs to 2.5V yourself, as this is not done internally on the analog board.
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We use the same differential line receivers on our analog encoder boards as we do on our digital encoder boards, so we can accept digital encoders properly on them. The pullup/down/termination loading is somewhat different, but for an encoder with reasonable drive capability, this should not matter. If it is a single-ended encoder, you will need to tie the "-" inputs to 2.5V yourself, as this is not done internally on the analog board.

 

Curt,

Will the Gate3[].Chan[].LossStatus still be valid for encoder fault detection in the condition described above?

Thanx

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The A+, A-, B+, and B- inputs do go to the XOR encoder-loss circuitry in the ASIC on the analog encoder board, as they do on the digital board. However, there are not pullup resistors to pull the lines high if not driven from the encoder. Instead, a termination resistor pulls the + and - pairs together when not driven. This should force them to the same state and trigger the loss-detection circuit, but we have not done real testing of this. It should be pretty simple to verify.
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