Renco Encoders

The Renco encoders supported by the TI-5000JX are tested as Generic Incremental Encoders and do not have a separate test. A section for them is included in this manual because, in the implementation used on Electrocraft motors, they have an important difference from standard quadrature pulse incremental encoders.

General Comments

Allen Bradley/Reliance/Electrocraft - Renco encoders encountered in servo motor repair are generally quadrature pulse incremental encoders. It is not uncommon for the Renco encoders to include U, V, and W commutation pulses as well. One such encoder, the RCH20D-2000/3-8MM-5/0-LD/VC-I-M6-S P/N 79994-004, is used with Electrocraft motors (and subsequently Reliance and AB due to corporate acquisitions). This encoder on these motors is supported by the TI-5019Q and 5045Q cables which will allow it to be tested as a quadrature pulse 8,000 count/rev encoder. This cable also provides a display of the U, V, and W (also designated S1, S2, and S3 or A, B, and C) commutation pulses as signals 1, 2, and 3 (4, 5, and 6 unused) in the Data Display function. In addition there is an analog output line (pin H) which produces distinct voltages for the 6 commutation steps. In one variation of the analog output, the commutation states and corresponding nominal analog voltages should be as follows:

When the motor is back driven and the analog voltage is viewed on an oscilloscope, it generates a stair step pattern. Each change in the stair step corresponds to a change in the commutation lines. Consult the manufacturer’s literature for details on specific models and series.

AB/Reliance/Electrocraft motors that are known to use this encoder are Series F, H, N S, and Y.

Giddings and Lewis – At least some G & L motors are very similar to the AB/Reliance/Electrocraft motors discussed above.

Other Variations - Another Renco encoder used with servo motors is the RHS21D-P1-2000-8MM-5-CS-LD-M1- 0-P-S P/N 79994-023. It may be used with Electrocraft or Giddings and Lewis motors. It produces A, B, and Z pulses but does not provide commutation pulses. It is supported by the TI-5018 cable which will allow it to be tested as a quadrature pulse 8,000 count/rev encoder. Note that the pin configuration for the 8 pin Amp connector is different than the configuration published by Renco for standard RHS series encoders. Standard Renco encoders use pin 2 for ground. The configuration used for this encoder is apparently proprietary to the motor manufacturer.

The pin configurations for these Renco encoders are shown in Section 2.9 and may be helpful if you encounter these encoders.

See Section 2.6.1 for more information on various Allen Bradley motors using Renco encoders.