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<blockquote data-quote="Glenn Adams" data-source="post: 138551" data-attributes="member: 6611">Re: Educate me:&nbsp; AES cablingLike this line?&quot;Cable does resist a signal, called impedance, depending in its length, thickness, capacitance and frequency being transmitted.&quot;Many devices have the terminator built in. Not so with DMX and I use RS485 in my day job all the time. I have runs of over 2,000 feet to PLC&#039;s in factories all over the world. &quot;NO T TAPPING&quot;. DMX has to use a terminator at the end of a run normally on the loop out of the last device. The receiver side of the signal and not the source side, hello!CCTV 75ohm devices normally have the end of line built in with a switch so you can lift devices loop thru as do many PLC&#039;s, Security panel, Fire panels, many still using RS 485 for communications loops. And a LOOP is not a T TAP.The main reason for the PAD at the end of any wire is to increase the drive voltages for longer distances. The pad knocks the voltage down to a usable level for the device input. As in the easy to see case of CCTV the drive voltage can be 2 volts, the input circuit will distort with a drive voltage that high. It wants to see 1.1 volt Peak to Peak max. Doing this helps signal to noise, surely a familiar term here. As the input circuit pads the signal down and the noise picked up along the way lowers as well.Yes, cable maters and mostly because high capacitance cable will turn a square wave into a camel hump quickly. Most data grade cable will have low capacitance. You can see the leading edge on a scope,&nbsp; &quot;| = best, / = not so much&quot;</blockquote>

[QUOTE="Glenn Adams, post: 138551, member: 6611"] Re: Educate me: AES cabling Like this line? "Cable does resist a signal, called impedance, depending in its length, thickness, capacitance and frequency being transmitted." Many devices have the terminator built in. Not so with DMX and I use RS485 in my day job all the time. I have runs of over 2,000 feet to PLC's in factories all over the world. "NO T TAPPING". DMX has to use a terminator at the end of a run normally on the loop out of the last device. The receiver side of the signal and not the source side, hello! CCTV 75ohm devices normally have the end of line built in with a switch so you can lift devices loop thru as do many PLC's, Security panel, Fire panels, many still using RS 485 for communications loops. And a LOOP is not a T TAP. The main reason for the PAD at the end of any wire is to increase the drive voltages for longer distances. The pad knocks the voltage down to a usable level for the device input. As in the easy to see case of CCTV the drive voltage can be 2 volts, the input circuit will distort with a drive voltage that high. It wants to see 1.1 volt Peak to Peak max. Doing this helps signal to noise, surely a familiar term here. As the input circuit pads the signal down and the noise picked up along the way lowers as well. Yes, cable maters and mostly because high capacitance cable will turn a square wave into a camel hump quickly. Most data grade cable will have low capacitance. You can see the leading edge on a scope, "| = best, / = not so much" [/QUOTE]

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