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What is the cause and method of rectifying Err 21.0 encoder communication line breakage fault protection, Err 21.1 encoder communication fault protection?

ID:
40389
Issued:
Apr 3rd, 2017
Updated:
Apr 27th, 2017

What is the cause and method of rectifying Err 21.0 encoder communication line breakage fault protection, Err 21.1 encoder communication fault protection?

ANSWER

■ Cause
Encoder communication line breakage fault protection Err21.0, and Encoder communication fault protection Err21.1 are generated if the serial data from the encoder has not been correctly received. The cause of failing to receive normal communication is indicated by Err21.0 for no response, and Err21.1 for faulty data. (Number of continuous failures to judge a fault is 6 times for A5, and 8 times for A6.)
■ Action
With A5 or A6, the number of communication faults can be checked using the “d22.rEc” monitor mode on the front panel.
With A5, if 1 to 5 communication faults are generated and increase with time, the cause is judged to be EMI. If six consecutive communication faults are generated, the cause is judged to be wire breakage or contact failure. The same logic applies to A6. If 1 - 7 consecutive communication faults are generated, the cause is judged to be EMI. Eight consecutive faults are judged to be wire breakage or contact failure.
(1) For EMI, check if the following EMI measures are effective.            
[1] Install a ferrite core (DV0P1460 by TDK ZCAT3035-1330) in the motor power line.
Install a ferrite core only on UVW lines excluding the grounding (E) line on the amplifier side (if possible). If using shielded wire, remove the shield. Including the grounding wire will restrict the EMI to flow to the actual grounding and the effect gets worse in some cases.
[2] Single-point grounding of the encoder cable shield.
If the amplifier and motor are separated, potential is generated in both units, and current starts to flow. If possible, disconnect the shield of the motor side encoder cable from the grounding connection of the motor encoder connector.
[3] Increase conductivity of the back surface of the servo-amplifier. Remove plating or paint.
[4] If the encoder cable is relayed in the middle, reduce the number of relays and use gold-plated connector contacts. (Unify the plating specifications)
[5] Use shielded, twisted-pair cable for the encoder cable and increase the density of the braided (shielding) jacket.
[6] If a long encoder cable is used, employ a thicker signal wire. Secure a motor-side encoder power voltage of 4.9 V or higher.
[7] Add 2 sq. mm FG wire between the motor and amplifier.
[8] Number of error counts for A5II and A6 may be increased 6⇒12 by using the functional expansion setting 2 Pr6.47 (change bit 2 to 1).
(2) In the case of contact failure, wire breakage, wiring error between the amplifier, encoder cable and encoder, apply external force or use a tester to uncover the cause.

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