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3.3 Encoder feedback signals EA, EB and EZ
The PCI-8136M provides 6 differential pulse inputs with 2500V rms isolation, and each pair of EA, EB, and EZ is related to one motion axis. The pulse mode is software programmable to be AB-phase, CW/CCW, or
Pulse/Direction, and the counter speed goes up to 2 MHz. The following table is the pin assignments for encoder counters.
Axis No.
27
28
29
30
31
32
77
78
79
80
81
82
33
34
35
36
37
38
83
84
85
86
87
88
CN1 Pin No. Signal Name
21
22
EA1+
EA1-
23
24
25
26
EB1+
EB1-
EZ1+
EZ1-
71
72
73
74
75
76
EA2+
EA2-
EB2+
EB2-
EZ2+
EZ2-
EA3+
EA3-
EB3+
EB3-
EZ3+
EZ3-
EA4+
EA4-
EB4+
EB4-
EZ4+
EZ4-
EA5+
EA5-
EB5+
EB5-
EZ5+
EZ5-
EA6+
EA6-
EB6+
EB6-
EZ6+
EZ6-
Description
Encoder A-Phase (+)
Encoder A-Phase (-)
Encoder B-Phase (+)
Encoder B-Phase (-)
Encoder Z-Phase (+)
Encoder Z-Phase (-)
Encoder A-Phase (+)
Encoder A-Phase (-)
Encoder B-Phase (+)
Encoder B-Phase (-)
Encoder Z-Phase (+)
Encoder Z-Phase (-)
Encoder A-Phase (+)
Encoder A-Phase (-)
Encoder B-Phase (+)
Encoder B-Phase (-)
Encoder Z-Phase (+)
Encoder Z-Phase (-)
Encoder A-Phase (+)
Encoder A-Phase (-)
Encoder B-Phase (+)
Encoder B-Phase (-)
Encoder Z-Phas e (+)
Encoder Z-Phase (-)
Encoder A-Phase (+)
Encoder A-Phase (-)
Encoder B-Phase (+)
Encoder B-Phase (-)
Encoder Z-Phase (+)
Encoder Z-Phase (-)
Encoder A-Phase (+)
Encoder A-Phase (-)
Encoder B-Phase (+)
Encoder B-Phase (-)
Encoder Z-Phase (+)
Encoder Z-Phase (-)
1
2
3
4
5
6
22
• Signal Connection
The input circuits of the EA, EB, EZ signals are shown as follows.
Figure 3.3.1 Pulse input (encoder counter) circuit
Note: The voltage across every differential pair of encoder input signals
(EA+, EA-), (EB+, EB-) and (EZ+, EZ-) should be at least 3.5V or higher. Therefore, you have to take care of the driving capability when connecting with the encoder feedback or motor driver feedback.
Here are two examples of connecting the input signals with the external circuits. The input circuits can connect to the encoder or motor driver, which are equipped with: (1) differential line driver or (2) open collector o utput.
Connection to Line Driver Output
To drive the PCI-8136M encoder input, the driver output must provide at least
3.5V across the differential pairs with at least 6 mA driving capability. The ground level of the two sides must be tight together too.
Figure 3.3.2 Connection to line driver output
Signal Connection
• 23
Connection to Open Collector Output
To connect with open collector output, an external power supply is necessary.
Some motor drivers also provide the power source. The connection between
PCI-8136M, encoder, and the power supply is shown in the following diagram.
Please note that the external current limit resistor R is necessary to protect the PCI-8136M input circuit. The following table lists the suggested resistor value according to the encoder power supply.
Encoder Power(VDD)
+5V
+12V
+24V
External Resistor R
0
Ω
(None)
1.8k
Ω
4.3k
Ω
Figure 3.5.3 Connect to open collector output
24
• Signal Connection
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