Input pulse levels
The evaluation electronics can process encoder signals (symmetrical as well as asymmetrical) up to a maximum differential voltage of 27 V. The encoder type is selected via parameter. The evaluation electronics are electronically adjusted to the encoder signal voltage. With the parameter setting, a sub-division is made into two rated input voltage ranges.
|
Rated input voltage range |
||
|---|---|---|
|
5 V |
15 V |
|
|
Low level |
Differential voltage < 0.8 V |
Differential voltage < 5 V |
|
High level |
Differential voltage > 2 V |
Differential voltage > 8 V 1) |
|
Hysteresis |
> 0.2 V |
> 1 V |
|
Common-mode controllability |
± 10 V |
± 10 V |
If the pulse encoder does not supply any symmetrical encoder signals, it must be grounded with each signal cable twisted in pairs and connected to the negative connections of track 1, track 2, and zero mark.
Maximum frequency that can be evaluated
The maximum frequency of the encoder pulses that can be evaluated is 300 kHz. To ensure that the encoder pulses are evaluated correctly, the minimum edge clearanceTmin between two encoder signal edges (track 1, track 2), as listed in the table, must be adhered to.
|
Rated input voltage range |
|||||
|---|---|---|---|---|---|
|
5 V |
15 V |
||||
|
Differential voltage2) |
2 V |
> 2.5 V |
8 V |
10 V |
> 14 V |
|
T min 3) |
630 ns |
380 ns |
630 ns |
430 ns |
380 ns |
If the pulse encoder is incorrectly matched to the encoder cable, disturbing cable reflections will occur at the receiving end. To ensure that encoder pulses of this type can be evaluated without errors, these reflections need to be damped. The limit values listed in the table below must be maintained in order to prevent the resulting power losses in the evaluation electronics adaptor from being exceeded.
|
F max |
|||||
|---|---|---|---|---|---|
|
50 kHz |
100 kHz |
150 kHz |
200 kHz |
300 kHz |
|
|
Differential voltage4) |
Up to 27 V |
Up to 22 V |
Up to 18 V |
Up to 16 V |
Up to 14 V |
Cable, cable length, shield connection
The encoder cable capacitance must be recharged at each encoder edge change. The rms value of this current is proportional to the cable length and pulse frequency, and must not exceed the current permitted by the encoder manufacturer. A suitable cable that meets the recommendations of the encoder manufacturer must be used, and the maximum cable length must not be exceeded.
Generally speaking, a twisted cable pair with a single pair shield is sufficient for each track. This reduces crosstalk between the cables. Shielding all the pairs provides protection against interference pulses. The shield should be connected to the SINAMICS DC MASTER shield bar through a large surface area.
1) Restriction: See “Maximum frequency that can be evaluated”
2) Differential voltage at the terminals of the evaluation electronics
3) The phase errorLG (deviation of 90°), caused by the encoder and cable and which may occur, can be calculated fromTmin:
LG = + (90° - fp Tmin 360° 10-6)
L G Phase error in °
f p Pulse frequency in kHz
T min Minimum edge clearance in ns
4) Differential voltage of the encoder pulses without load (approximate encoder power supply voltage)