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Optocoupler interface
Optically isolated inputs and outputs.
Optocoupler basics
Diagram of basic optocoupler function
An optocoupler is a device using optical path to transfer an electronic signal between two circuits. It basically consists of a photodiode beween pin 1 and 2 converting the input signal to light and a phototransistor converting the light again to electronic signal at pin 3 and 4.
The optocoupler is useful in situations where one part of the circuit needs to be galvanically isolated from the other part to prevent damage or unwanted interference. It is used to prevent ground loops or to block voltage spikes.
For effective use of the optocoupler it is important to control it using an independent power supply. When the external circuit is galvanically connected to the camera (eg. when reusing the camera's power to control the optocoupler), the optocoupler's protective function is eliminated.
Optocoupler inputs
The iam camera camera is equipped with four optically isolated input lines. One input optocoupler is fully independent, the other three are connected with a common cathode (Section “I/O connector”) due to limited number of pins on the I/O connector. Each input line is protected by a current limiter circuit.
The optocoupler input's logical state is understood as logical 0 if no current is flowing through the optocoupler diode, logical 1 if current is flowing through the diode.
The optocoupler is guaranteed to be switched on (logical 1 status) when the voltage applied to the input is within range of 3.3 - 30V (tolerance 10%). It is guaranteed to be switched off (logical 0) when the applied voltage is under 2.0 V. The input status is undefined between 2V and 3 V,the input voltage must not exceed the 30V limit!
The input lines are using fast optocouplers: the propagation time is under 125 ns, for both rising and falling signal edge (assuming input signal with strongly steep edge). The exact switching speed may vary with temperature and the used input voltage level - the listed specifications are the worst case values.
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The optocoupler inputs have no protection against wrong polarity. Be sure to connect them always with correct polarity according to the documented wiring diagrams and connector pinouts. |
The optocoupler inputs are TTL compatible provided that the signal source is capable of supplying the input current of 7.5 mA.
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The optocoupler input lines are equipped with a debouncer to prevent generating unwanted input signals. |
Optocoupler outputs
The iam camera is equipped with three optically isolated output lines. One output optocoupler is fully independent, the other two are connected with a common collector (Section “I/O connector”) due to limited number of pins on the I/O connector.
After power up, the optocoupler outputs are in high impedance state and they remain in that state until reconfigured from the software interface. Whenever the optocoupler output is disconnected in the SW interface, it gets in high impedance status.
- optocoppler high impedance state: ist das so schon? Andreas Kramer | NET GmbHmartin.winterer (Unlicensed)
The optocoupler output's logical state is understood as logical 0 when its output transistor is in high impedance, logical 1 if it is in low impedance mode.
The rising edge (switching to logical 1) propagation time is 750 ns, the falling edge propagation time is under 25 µs. The exact switching speed may vary with temperature and the used input voltage level — the listed specifications are the worst case values.
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The optocoupler output work with operating voltage range of 3.3-30 V. The maximal switched output current is 100 mA per optocoupler, higher current could damage the optocoupler output circuit. |
Optocoupler parameters summary
Parameter
INPUT Value
Output Value
Operating voltage
3.3 - 30 V
3.3 - 30 V
Input current
7.5 mA
< 100mA
External resistor requirement
No
Yes, output current must be limited to 100 mA
ON voltage level
> 4.5 V
OFF voltage level
< 1.5 V
OFF to ON delay
< 125 ns
750 ns
OFF to ON rise time (10 to 90%)
1.0-4.0 µs
ON to OFF delay
< 125 ns
2.4 – 25 µs
ON to OFF fall time (90 to 10%)
9.0 – 140 µs
OFF to ON jitter
± 5 ns
± 20 ns
ON to OFF jitter
± 5 ns
± 0.1 µs
Connector and cable description
14-pin DLP (dual-inline-pin) connector for digital i/o and power input. An adapter cable is available (see Section “Accessories”).
Connector Pinout TFM-107-02-L-DH.pdf
Mates Pinnout SFSD-07-XXX-G-XX.XX-SR
view manufactor information (external link)
Pinnout
Pin #
Schematic Name
note
1
AUX_POWER
auxiliary power supply voltage
2
GND_P
auxiliary power supply Ground
3
IN_TRIGGER+
Optocoupler Input TRIGGER Anode
4
IN_TRIGGER-
Optocoupler Input TRIGGER Cathode
5
IN_ENC1+
Optocoupler Input 1 Anode
6
IN_ENC2+
Optocoupler Input 2 Anode
7
IN_ENC3+
Optocoupler Output 3 Anode
8
IN_ENC_GND
Optocoupler 1-3 Input Cathode
9
OUT_GP1+
Optocoupler Output 1 Collector
10
OUT_GP2+
Optocoupler Output 2 Collector
11
OUT_GP_GND
Optocoupler Output 1-2 Emitter
12
OUT_STROBE+
Optocoupler Output STROBE Collector
13
OUT_STROBE-
Optocoupler Output STROBE Emitter
14
SGND_IO
Cable Shield
Accessoires
Break-Out-Boards
Cable Assemblies
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Introduction
This section describes all types of input and output signals available with iam, including their characteristics and when necessary including connection examples. Location and pinouts of the connectors carrying the signals are documented in Mechanic and Connector and cable description.
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🔍 References
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👥 contact NET
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