Challenges in Testing /Aligning Encoders
Heidenhain ERN 1387 | Hengstler S21-2028.001/03 | and Heidenhain EnDat Encoders
& our Preparedness for that
1V p-p differential signal
The encoder ERN 1387 is an incremental-type encoder. Incremental signals are sin-cos signals. The 1Vpp signals need to be amplified to be 5v input compatible for further testing.
We have Specially built Amplifiers for 1 V p-p A and B channel encoder signals with a 3.8 gain to be 5V input compatible for further testing
Ern1387 encoders produce a 1V p-p differential signalThe differential amplifiers amplify this signal up to nearly 4 V p-p differential signals biased upto about 2.5 VDC. The amplified signal appears on the channel true line and a 2.5 VDC bias signal appears on the channel complement line. These levels are more compatible with the 5 V logic inputs of the Encoder testers.
The C and D commutation channels :
These Incremental rotary encoders with a second track—the Z1 track—provide one sine and one cosine signal (C and D) for each motor shaft revolution in addition to the incremental signals. For sine commutation, rotary encoders with a Z1 track need only a subdivision unit and a signal multiplexer to provide both the absolute rotor position from the Z1 track with an accuracy of ± 5° and the position information for speed and position control from the incremental track Some rotary encoders feature additional commutation tracks for sensing the rotor position during switch-on.
We have special modules to Route 1 V p-p C and D encoder commutation channels to the AjFET Servo tester inputs to check the commutation angle.
In case where your AC Servo motor is fitted with an ERN 1387; we have a 1Vp-p Amplifier Adapter Module with Sin/Cos Commutation Support to interfaces 1Vp-p sine wave encoder signals to our Encoder tester.
It also allows for reading of the commutation angle generated by Heidenhain ERN1387 C&D channels used on Siemens motors. The low level 1Vp-p signals are amplified by a gain of 3.8V using differential amplifiers which help reduce noise problems during a runtest.
Running of the motors:
We can also Test run the motors fitted with Ern1387 Encoder. The low level 1 V p-p signals are susceptible to noise pickup. Large motors running on the Testing Systems, may pick up enough drive noise that they do not run correctly. We have a Module in our kit, in which The differential amplifiers in this module tend to cancel out the common mode noise on the true and complement lines so that the
motors run smoothly.
Table 6. Match between connector/color of the wires of pulse generator ERN 1387 with signals transmitted by the inverter
|Signal : Up sensor @ Encoder pin 7a
|commutation channel outputs Signal: C+ @ Encoder pin 7b
|Signal :Up @ Encoder pin1b
|commutation channel outputs Signal: C- @ Encoder pin 1a
|Signal :0 V Un @ Encoder pin5b
|commutation channel outputs Signal: D+ @ Encoder pin 2b
|Signal :0 V @ Encoder pin3a
|commutation channel outputs Signal: D- @ Encoder pin 6a
|ounting channel outputs Signal :A + @ Encoder pin6b
|reference channel output. Signal: R+ @ Encoder pin 4b
|counting channel outputs Signal :A – @ Encoder pin2a
|reference channel output. Signal: R- @ Encoder pin 4a
|counting channel outputs Signal :B + @ Encoder pin3b
|counting channel outputs Signal: B- @ Encoder pin 5a