You have to add some circuitry. The IC AM26LS31 has TTL compatible inputs and RS485 compatible differential outputs which will be compatible with the UMI box.
Using differential signals is recommended when you have long signal lines, the differential signal transmission is much less sensitive to environment noise. You should use twisted pair cables if possible. Of course the TTL-to-differential-signal-converter should be located as close as possible to the encoder.
1. You have to connect the /G input to GND.
2. You mention the A channel only. The NI boards will accept signals from incremental encoders only, so there should be a B channel output on your encoder as well?? You can use the second half of the AM26LS31 to convert the B output signals.
please explain principles of brush servo control . How to control voltage at analog output(DAC CHANNEL) when i choose servo external commutation on axis configuration on MAX.
oops ... should read "one more converter circuit contained in the AM26LS31" instead of "the second half". The AM26LS31 contains four converter circuits for TTL to RS485 signal conversion.
There is no need for connecting unused inputs via pull-up resistors to +5VDC or directly to GND, the AM26LS31 has pull-up resistors on all inputs.