Allen-Bradley 1756-CFM, Руководство пользователя

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Rockwell Automation Publication 1756-UM010C-EN-P - June 2021 121
Appendix C Module Schematics
Series B Module
To turn on a gate circuit, you must source current through the input resistors
sufficient to turn on the Q3 and opto-isolator in the circuit. Operating current
range for this new input circuit is 5…8mA. If no connection is made to the pair
of gate terminals, no current flows through the photodiode of the opto-isolator
and that gate IS OFF (the corresponding input status indicator is OFF).
The photodiode, combined with Q3, requires approximately 1.8V DC total to
switch ON. Q15 works as constant current source and maintains constant
current flow of approximately 4mA across photo diode. R65 is around 93 Ω and
Q3 maintains approximately 0.4V drop across it.
The input current magnitude can be determined by:
IMPORTANT This schematic represents the Series B module
Z0 RET
Z1 RET
physical and electrical isolation
Z0 (5V)
Z1 (5V)
2
1
Input
6
5
RET
D21
R193
R177 R65
4
3
Z0 (12-24V)
Z1 (12-24V)
1 mA
R178
R158
R86
D15
D2
D43
Q15
Q3
CASE A – for 5V DC operation CASE B – for 10 V DC to 31.2 V DC operation
Gate input current =
93  550  93 
1. There is approximately a 0.4V drop across R65 that is
maintained by Q15 constant current source. A minimum of
4.5V is required to turn on the Input circuit.
Examples
(3V
1
)
If gate input voltage = 10V DC
Gate input current = 4.6 mA
Examples
If gate input voltage = 31.2V DC
Gate input current = 6.6 mA
(0.4V
1
) Voltage Drop across Resistor in series with Q15
1
Gate input current =
Gate input current =
550  93 
(4.29V
1
)
Gate input current =
550  93 
1. There is approximately a 2.5...4.5 V drop across Resistors in series with Q15 that is maintained by Q15
constant current source. A minimum of approximately 7.5V is required to turn on the Input circuit.