Knowledge Base

Pulse Sequences

Aim

To specify a train of pulses of frequency up to 0.5 kHz.

The Pulser Software

The Pulser/PulserPlus can send out a very specific modulated pulse sequence. You can program the Pulser by specifying a number of parameters in a command line (string command; see below). This command line is sent out from EthoVision XT to the Pulser.

Structure of the Pulse Sequence

Pulse train. Two pulses (1 and 2) are organized in a pulse train. This is described by the following parameters:

• The duration of pulse 1 (P1D).
• The interval between pulse 1 and pulse 2 (P1I).
• The duration of pulse 2 (P2D).
• The interval between pulse 2 and the end of the train (P2I).
• The interval between trains (BI).

Number of trains. A pulse train can be repeated a number of times specified by the parameter TNT. The total duration of the signal is given by TNT times the total duration of the other five parameters.

Group of pulse trains. A number of trains defined as above can be seen as a group. The duration of the group is defined automatically by the parameters above. Multiple groups of pulse trains are therefore defined by the interval between groups (GI) and the total number of groups (TNG).

Structure of the String Command

Where:

• echo — DOS command that sends the string.
• M — Command prefix. Do not put commas between this and the next parameter.
• TNT — Total number of trains.
• BI — Interval between trains (msec).
• P1D — Duration of pulse 1 (msec).
• P1I — Interval between pulse 1 and 2.
• P2D — Duration of pulse 2 (msec).
• P2I — Interval between pulse 2 and end of train (ms).
• TNG — Total number of groups of pulse trains.
• GI — Interval between groups (sec).
• OM — Operational mode. For Pulser [0,1,2,3], for PulserPlus [100 to 103], where:
  • 0 (100) = Do not use the trigger input.
  • 1 (101) = Use the trigger for single sequence.
  • 2 (102) = Use the trigger. Perform the sequence and when finished wait for the next trigger.
  • 3 (103) = Use the trigger. Perform the sequence as long as the trigger is "high". This is the recommended option.
• NoT — Number of triggers [1, 2, ...].
• ToDy — Delay of TrigOut from last train finish (not used by EthoVision XT).
• ToDu — Duration of TrigOut (not used by EthoVision XT).
• ToIt — TrigOut interval (not used by EthoVision XT).
• ToNu — Total number of TrigOut (not used by EthoVision XT).
• @ — End of command (no comma before it).

See also the Pulser/PulserPlus User Manual.

Example

In an optogenetics protocol we want to stimulate the animal with light bouts of 20 ms separated by 20 ms off. This would result in 25 Hz stimulation. P1D = P2D = P1I = P2I = 20 ms.

The resulting string command to send to the Pulser (note: OM = 3 for Pulser, 103 for PulserPlus):

Notes

• Although the total number of trains TNT is set to 1, the pulses are sent out continuously because the operation mode is set to 3. In this case the pulse trains are generated as long as EthoVision XT sends the TTL signal "high". When EthoVision XT sends the TTL signal "low", the sequence stops.
• If one wants to stimulate the animal as long as the animal is in a specific zone, in the Trial Control Settings the TTL signal "high" must be associated with a condition based on the variable In Zone.
• With operation mode 3, during generation of the pulse sequence the LED is lit on continuously.
• If you have the Pulser and the older Pulser software (version 2.1), the command above would be: echo 1,0,20,20,20,20,1,0,3,1@.

Configure the COM Port for Each Pulser

Aim

To configure the COM port in such a way that the Pulser/PulserPlus accepts commands from EthoVision XT.

Procedure

1. Connect the Pulser/PulserPlus to the PC using the USB cable (type-A to type-B connectors).
2. In the Control Panel, open the Device Manager.
3. Under Ports (COM & LPT), right-click USB Serial Port and select Properties.
4. Click the Port Settings tab.
5. Make sure that the parameters are set correctly, then click OK.
6. Take note of the port number.
7. Repeat the procedure for each Pulser/PulserPlus.

Notes

• The COM port number is retained in the Pulser, so if you disconnect the Pulsers and reconnect them, you do not have to assign the COM ports again.
• Tip: To determine which COM port is assigned to a Pulser/PulserPlus device, disconnect the USB cable from the Pulser/PulserPlus, then reconnect it. The item that appears under Ports (COM & LPT) indicates the COM port.
• Tip: To change the COM port for a specific Pulser, open the Device Manager from the Control Panel. Under Ports (COM & LPT), right-click the COM port, select Properties, then Port Settings, then Advanced. From the COM Port Number list, select the desired COM port from those available.

Program the Prizmatix Pulser/PulserPlus Within EthoVision XT

Aim

To program the pulse sequence.

Prerequisites

• The Pulser driver is installed.
• The COM port is configured as described in the COM port configuration section.
• Important: Make sure that Custom Hardware is selected in the EthoVision XT Device Configuration window, not TTL Tester or others.

Procedure 1 - Initialize the COM Port

In EthoVision XT, open the experiment and choose Setup > Trial Control Settings > New. Follow all instructions below.

1. Under Actions, choose External command.
2. Next to Select program to run, browse to C:\Windows\System32\cmd.exe.
3. Add the Command line options as follows:
   /C mode COMn BAUD=57600 PARITY=N DATA=8 STOP=1 DTR=off RTS=off
   • Important: In place of n, enter the number of the COM port for that Pulser.
   • Note 1: The command /C closes the window after sending the command line.
   • Note 2: If you have the Pulser and the older Pulser software (version 2.1), the command above would be: /C mode COMn BAUD=57600 PARITY=N DATA=8 STOP=1 DTR=on.
4. Click OK and insert the resulting box after the Start Trial box.
5. Under Conditions, choose Time.
6. In the Time Condition window, select After a time of 2 secs.
7. Insert the Time Condition box after the Action box.

Source: EthoVision XT 18 - Application Manual, Noldus Information Technology