Mitsubishi NZ2GFCF-D62PD2 User Manual page 231

Check item
Does the input pulse waveform meet the performance
specifications?
Does the other channel show the same count result
when the same input is applied to the other channel?
● How to fix pulse form
This portion describes how to fix pulse waveform by dummy resistance that can be used against noises from outside or
distortion of pulse waveform.
To fix pulse waveform effectively, increase load current inside cables by applying dummy resistance of several hundreds
ohms (/several W) between the pulse input terminals connected to the encoder. The greater the load current, the more
effective this method is.
● Effect
• When the distance between the encoder and the high-speed counter module is long
Distortion of waveform is fixed and the pulse waveform becomes stable.
• When the pulse waveform is distorted due to noises from outside
Taking the method above stabilizes pulse waveform; distortion of pulse waveform by noise can be reduced.
● Example of dummy resistance at 24VDC
High-speed counter module
Phase A
Phase B
● How to choose dummy resistance
The following example describes how to choose the required resistance amount and rated-standard electricity of dummy
resistance.
<Example>
• How to calculate the dummy resistance amount (at 24VDC)
Calculation: R = V ÷ I = 24V ÷ 35mA = 680 Ω
• How to calculate rated-standard electricity (at 24VDC)
Calculation: P
Calculation including a margin: P
Result: Install dummy resistance of 680Ω (/2W) in between the pulse input terminals.
Check the pulse waveform with a synchronoscope. If the input pulse does not
meet the performance specifications, input pulses which meet the performance
specifications.
If a different count value appears, a module failure may be the cause. Please
consult your local Mitsubishi representative.
DIF
B19(B13)
5V
A20(A14)
24V
B20(B14)
240 270 4.1k
820
COM
A19(A13)
DIF
B17(B11)
5V
A18(A12)
24V
B18(B12)
240 270 4.1k
820
COM
A17(A11)
= V × I = 24V × 35mA = 0.84W (approximately 1W)
1
= P
2
Action
Put dummy resistance of several
hundreds ohms (/several W)
between the pulse input terminals,
24V and COM.
Shielded twisted pair cable
× 2 = 0.84 × 2 = 1.68W (approximately 2W)
1
CHAPTER 11 TROUBLESHOOTING
24V
OUT
24V
OUT
E
229
11