All of the NI 951x Modules have the same pins in use for Encoder 0, so we will discuss all three together. The NI 9516 provides connection for a second encoder to perform dual encoder feedback. The connection for the NI 9516 Encoder 1 is the same as Encoder 0 except that Encoder 1 does not contain an Index line.
For the purposes of this tutorial, we are assuming that you are using the NI 951x 37-pin Terminal Block. If you are creating custom cabling for your motion system, refer to Chapter 4, Accessory and Cable Connections, in the NI 951x User Manual for additional wiring information.
We have eliminated all of the irrelevant terminals from the pinout diagram for this example. The colors that we are using in these examples for wires are not indicative of the colors you may encounter. There are no standard colors for each line of an encoder, and your encoder may be different.
First, we will take a look at wiring to a differential encoder, one which has a plus and minus wire for each line of the encoder: A, B and Index. In these diagrams, and commonly in industry, the Index line is referred to as the Z line.
Some encoders use only one wire for each line and have a common ground for all of the lines together. This can be handled by the 951x Terminal Block by wiring the ground line of the encoder into each minus pin of the terminal block. Any methodology for tying all of the minus lines together will accomplish this successfully. This is shown below.