PCIe 6536b with differencial signals

[waroliver]

I would like to use the PCIe 6536b card to read some high speed A Quad B  signals from an encoder.  The signals are differential. A+, A-,B+, B- and a differential clock signal.  I cannot find how to connect things when the signals are differential rather than single ended. Do I need additional hardware to convert to single ended signals or can the 6536b handle these signals on it's own?  Thanks

[Buechsenschuetz]

I cannot see any specs for differential inputs in the datasheet so most probably the inputs are for single-ended TTL level only. You have to use a differential-to-TTL signal converter. You can build your own with the Am26LS32 ics, or buy a ready-made unit. We are using signal converters from german manufacturer LEG Electronics. There are other manufacturers making similar devices. https://www.leg-gmbh.de/en/SU3-en.pdf

BTW are you sure that the third signal channel is a "clock channel"? Encoders usually are asynchronous devices and do not need or generate a clock signal, but most of them generate an index pulse on a third channel which is activated once per revolution and allows for precise positioning/referencing of drive systems. 

[waroliver]

The signals I am using are coming from a laser interferometer.  They mimic A Quad B but are very fast.  I am not an expert but I think they provide some additional signal to make sure things work well even at high frequencies.  I will check out the converters.  Thanks

[Buechsenschuetz]

I see... so your device emulates the encocer channels A and B only and the third channel seems not to be related to position detection. So the third channel probably can not be connected to the index channel of the Motion Controller but rather to one of the digital Inputs. But it has to be converted to TTL level signal too.