Electro Cam PS-2252-12-PT1 NFEI - Manual (Page 2)

R C S + O B A R C S + O B A
Reset Reset
Reset Input Common Reset Input Common
Reset Input, Sourcing Reset Input, Sinking
Mechanical Switch Mechanical Switch
Solid State Switch
OR OR
Solid State Switch
PNP Transistor NPN Transistor
- -
R C S + O B A
Overflow Out 0 CHN B (from encoder) CHN A (from encoder) +11-15 VDC IN
-
Not Used Shield Common Reset
For Example:
A quadrature encoder with 1000 pulses/revolution has 4000 edges
revolution
If this encoder revolves at 800 rev/min:
800 rev . 1min . 4000 edges = 53,333 edges
min 60 sec
1 rev sec
This implies 18.75 microseconds
edge
Thus, the upper speed limit for a 1000 rpm quadrature encoder is 800 rpm.
Troubleshooting
S ymptom: Output does not turn on with encoder movement.
a. Verify that the voltage on the + and - terminals of the NFEI terminal block is between 11 and 15 VDC.
b. Verify with oscilloscope that proper encoder signals (per Internal Encoder Count illustration) are present at the Chn A
and Chn B terminals of the NFEI terminal block, and that the voltage levels are TTL compatible (logic 0 less than 0.8 v
and logic 1 greater than 2.0 v). If not, there is a problem with the encoder or encoder cable. If the encoder signals are
proper, the problem is internal to the NFEI, and the NFEI should be exchanged.
c. Verify that the configuration DIP switch setting agrees with the actual direction of encoder movement. If the Overflow
output is at a TTL high level, then the encoder has moved more than 65,535 counts in the reverse direction, and the
internal reverse count logic of the NFEI will not be accurate. Move encoder to “0” position and reset NFEI.
d. Verify with oscilloscope the status of the Out 0 terminal on the NFEI terminal block. If, after the reverse counts have
been counted out, there are pulses when the encoder moves in the configured direction, then the problem is not in the
NFEI.
Internal Encoder Count
Mechanical oscillation of the encoder is properly tracked by the NFEI as long as the minimum
time between encoder channel edges is within specification, as illustrated below.
A
B
17 microseconds minimum
Installation
Connect the NFEI using the Terminal Block Wiring illustration below.
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