Encoder Output Type

[Donovanr 0]

Hi All I am looking at installing an SEW Motor/gbox and Encoder to a Powerflex 40P drive using positioning, The recommended Allen Bradley encoder is a 845T-DB12EFW which is DLD (Differential Line Driver 5VIn - 5VOut) SEW have an encoder which an ES1T which is TTL (Transistor Transistor Logic 5VIn - 5VOut) Is DLD and TTL the same? Thanks

[KidPLC 2]

Hi Donovanr, I think you will be able to use the ES1T just fine......don't forget to set the voltage dip switch on the Powerflex to 5VDC though. Typical TTL voltage is 0v to 0.8v is a "low" and 2.2 to 5v is a "High" I agree the terminology used is a little confusing, I will attempt to unravel a bit of it with my limited knowledge (maybe there are some guys out there that can go a little deeper on this subject). The PowerFlex Drive will process the A and -A signals from the Encoder via a Differential Amplifier (put really simply and op-Amp device made up of heaps of tiny transistors inside). The voltage level at the -A signal is the inverse of the voltage level at the A signal. The differential Amp will look at the difference between these two voltages and output a single signal to the down stream circuitry of the drive positioning/speed/direction system. If noise is imposed on the twisted A and -A pair then it will be nulled out by the action of the Differential amplifier because each wire will carry the same amount of noise equally therefore the overall difference the amp is trying to measure remains the same. The B and -B and Z and -Z signal are processed in the same way. So when the AB encoder says it has the DLD output it simply means it can provide an A and -A signal etc. It will have to use some electronic component to get the signal out of the encoder and this will most likely be transistors or maybe FETs but it doesn't matter. The SEW encoder uses TTL which means it is using transistors and the voltage level will be at the TTL range (see above) also in the specs it says it can provide A, -A, B, -B etc so in effect it is a DLD as well because it is providing differential outputs. Hope this helps Edited 14 May 2008 by KidPLC

[Donovanr 0]

Edited 14 May 2008 by Donovanr

[Kiwi Sparky 0]

How did you get on with the SEW ES1T Encoder? I am about to do a basic positioning project with a Powerflex 40P and SEW Motor Gbox and need to purchase the SEW equipment soon. If this did not work for you, I will purchase the AB encoder instead

[Donovanr 0]

I ending up using a Stegmann Encoder part. DRS60-A4A01024 half the price of AB and SEW encoders.. However it needs its own mounting to the motor shaft Just in the middle of commissioning a few 40P's using positioning..