Koheron CTL200 User manual

CTL200 User Guide
This user guide is for the CTL200 v5+. For previous versions, please refer to the <v5 guide.
Laser connections
The CTL200-1 / CTL200-2 is compatible with Type 1 / Type 2 butterfly laser diodes. Note that it is compatible
with floating diodes.
Butterfly laser type 1 pin configuration
1 / 6
CTL200
www.koheron.com

Butterfly laser type 2 pin configuration
Terminal block connections
RX, TX: Serial interface pins.
AI1, AI2: Auxiliary analog inputs between 0 and 2.5 V.
DO1, DO2: Digital outputs that replicate the status of LASER and TEMP LEDs on 3V3 logic levels.
LCK: Interlock pin.
VCC: 3V3 output supply pin. This pin is not designed to supply the CTL200.
Power supply
The CTL200 is provided with a 5.9 V / 3 A power supply. The CTL200 is supplied with 5 V or 6 V via the barrel
connector. With 5 V power supply, compliance voltages are reduced by 1 V. To supply the board with 5 V supply,
set the SW3 position to ON.
Important note: The VCC pin on the terminal block is not designed to supply the CTL200.
Configuration switch
Switch 1: When SW1 is ON, the user configuration is loaded at start-up. When SW1 is OFF, the default
configuration is loaded at start up.
Switch 2: SW2 is used for firmware update. It should be kept OFF for normal operation.
Switch 3: SW3 is used to switch between power supplies. Set SW3 to ON when supplying the CTL200 with
a 5 V power supply.
Switch 4: Unused.
Serial interface
The serial interface can be accessed either via the micro USB connector or via the TX and RX pins of the terminal
block (3V3 logic level / 5V tolerant).
The serial interface is the only way to configure the CTL200 operating parameters. Once the configuration is
done, it can be saved to the internal memory with the save command. If the configuration switch SW1 is ON at
2 / 6
CTL200
www.koheron.com

start up, the CTL200 will load the user-defined configuration and the serial interface is no longer needed.
The CTL200 can be controlled directly from a serial port terminal (e.g. Teraterm on Windows) with the following
configuration:
Baud rate: 115200
Parity: None
Bits: 8
Stopbits: 1
Flow control: None
Note: If your computer does not recognize your controller, please see also this FAQ.
Example use of the serial port terminal
>>
>>version
V0.1
>>rtset
10000.000000
>>rtact
10000.023438
>>rtset 12000
12000.000000
>>rtact
11999.853516
Note: Each command must be followed by \r\n.
Graphical User Interface
A Graphical User Interface is available for Windows. The installer can be downloaded at this link. The GUI
provides an effective mean of tuning the PID gains of the temperature controller.
Commands
Command Description Type Unit Default Min Max
lason Disable | enable laser current R/W 0 0 1
ilaser Laser current. R/W mA 0.0 0.0
vlaser Laser voltage R V
ldelay Time between when the controller lights up and
when the laser lights up R/W ms 1000.0 10.0 100000.0
3 / 6
CTL200
www.koheron.com

ilmax Software current limit R/W mA 1000.0 0.0 1000.0
lckon Disable | enable interlock functionality R/W 0 0 1
lmodgain Laser current AIN1 modulation gain R/W mA/V 0 -
100000.0 +100000.0
tecon Disable | enable TEC current R/W 0 0 1
tprot Disable | enable temperature protection R/W 1 0 1
rtset Thermistor resistance setpoint R/W Ω 10000.0 rtmin rtmax
rtact Actual value of thermistor resistance R Ω
itec TEC current R A
vtec TEC voltage R V
pgain Proportional gain of the temperature controller R/W 0.001 0.0 0.1
igain Integral gain of the temperature controller R/W 0.0001 0.0 0.1
dgain Differential gain of the temperature controller R/W 0.005 0.0 0.1
rtmin
Minimum thermistor resistance. If temperature
protection is enabled, the laser current is
automatically disabled below this value.
R/W Ω 5000.0 2000.0 50000.0
rtmax
Maximum thermistor resistance. If temperature
protection is enabled, the laser current is
automatically disabled above this value.
R/W Ω 15000.0 2000.0 50000.0
vtmin Minimum TEC voltage R/W V -2.0 -3.0 0.0
vtmax Maximum TEC voltage R/W V 2.0 0.0 3.0
tmodgain Temperature AIN2 modulation gain R/W Ω/V 0 -
100000.0 +100000.0
iphd Photodiode current R mA 0.0 2.5
ain1 AI1 pin voltage R V 0.0 2.5
ain2 AI2 pin voltage R V 0.0 2.5
tboard Board temperature R °C
version Firmware version R v0.17
status Return lason, vlaser, itec, vtec, rtact, iphd, ain1,
ain2.R
save Save configuration in internal memory (no
argument) W
serial Return the serial number R
userdata
write Write the user data (e.g. userdata write ABC) W 31 chars
4 / 6
CTL200
www.koheron.com

userdata Read the user data R
brate UART baud rate R/W baud 115200 9600 460800
err Return the error code in hexadecimal format (no
argument) R
errclr Clear the error code (no argument) W
Status LEDs
STATUS: Always ON during normal operation. Blinks when an error is detected (err > 0).
LASER: Turns ON when the photodiode current is above 10 µA.
TEMP: Turns ON when the thermistor resistance is within 1 Ω of the setpoint.
The digital outputs DO1 and DO2 replicate the status of LASER and TEMP LEDs on a 3V3 logic level.
Error codes
The command err returns a 32-bit number in hexadecimal representation which concatenates the detected errors
(B0 is the Least Significant Bit):
B0: UART_BUFFER_OVERFLOW (err = 1)
B1: UART_CMD_BEFORE_PROMPT (err = 2)
B2: LASER_UNDERTEMPERATURE (err = 4)
B3: LASER_OVERTEMPERATURE (err = 8)
B4: CMD_UNKNOWN (err = 10)
B5: CMD_INVALID_ARG (err = 20)
B6: LASER_ON_WHILE_INTERLOCK (err = 40)
B7: INTERLOCK_TRIGGERED (err = 80)
Modulation inputs
The CTL200 has two current modulation inputs available on SMA connectors:
DC modulation input for modulation between DC and 10 MHz. A jumper allows to choose between 3
modulation gains (Low = 250 µA/V, Medium = 2.5 mA/V or High = 25 mA/V for the 200 mA version).
Modulation range is between -1.3 V and +1.3 V for the Low and Medium modulation gain and between -1.3
V and 1.0 V for the High modulation gain (50 Ω input impedance).
AC modulation input for modulation above 100 kHz. Modulation range is ±5 V (50 Ω input impedance).
Modulation gain is 20 mA/V.
Thermal management
The TEC voltage limits (vtmin and vtmax) and the thermistor resistance limits (rtmin and rtmax) provide an
effective way of protecting the laser against thermal runaway. For reliable operation, the aluminium cooling base
plate must be properly heatsunk.
5 / 6
CTL200
www.koheron.com

Interlock
An optional interlock functionality can be activated with the lckon 1 command. Laser current is then disabled
when the LCK pin is pulled low. The figure below shows the use of the interlock with an external opto-isolator:
Once laser current has been disabled, the serial command lason 1 must be sent to re-enable the laser current.
The behavior of the interlock pin can be inverted with the command lckon 3.
Analog modulation with AIN1 and AIN2
The analog input AIN1 can be used in conjunction with the command lmodgain (in mA/V) to modulate the laser
current: ilaser' = ilaser + lmodgain x (V_AIN1 - 1.25 V) .
The analog input AIN2 can be used in conjunction with the command tmodgain (in Ω/V) to modulate the laser
temperature: rtset' = rtset + tmodgain x (V_AIN2 - 1.25 V) .
6 / 6
CTL200
www.koheron.com