Using the USB Trigger Interface as a Parallel Port

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raj_aiyer
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Joined: Tue Jan 07, 2020 11:51 am

Using the USB Trigger Interface as a Parallel Port

Post by raj_aiyer » Tue Jan 07, 2020 11:57 am

Hello,

I have been working on getting some triggers sent on the USB trigger interface. I realise it is recognised by the computer as a serial port. I am able to send triggers, but am not seeing them reflected in ActiView. The current solution I have for sending triggers only allows string values on serial ports (this is a different matter entirely!), which means we would have to either figure out how we can change the way in which BIOSEMI interprets values it receives or we would have to somehow use the serial port as a parallel instead. Is there a BDF reader can convert strings into byte values? Alternatively, could we somehow make it such that the USB trigger interface is used as a parallel port for sending byte values rather than strings? Many thanks in advance!

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Gerben
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Joined: Fri Sep 24, 2010 4:36 pm

Re: Using the USB Trigger Interface as a Parallel Port

Post by Gerben » Tue Jan 07, 2020 3:30 pm

Hello,

The Biosemi USB trigger interface expects a single byte containing the trigger value in a unsigned binary format (uint8_t).
Sending a ASCII encoded string containing the trigger value will violate the timing constrains for the trigger input and cause incorrect behaviour.
Is there a BDF reader can convert strings into byte values?
This is not possible, the BDF reader can not see the original string and the string contained in the bdf file is most likely incomplete due to timing violations.
Alternatively, could we somehow make it such that the USB trigger interface is used as a parallel port for sending byte values rather than strings?
The USB trigger interface can not act like a virtual parallel port because of driver constrains, but the USB trigger interface already accepts byte values as input on the virtual serial port.

The only option would be that you (or the manufacturer of your trigger software) modify the trigger software to send the triggers in a different format.

Best regards, Gerben (Biosemi)

raj_aiyer
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Joined: Tue Jan 07, 2020 11:51 am

Re: Using the USB Trigger Interface as a Parallel Port

Post by raj_aiyer » Wed Jan 08, 2020 12:57 pm

Hello Gerben,

Many thanks for your reply. I have seen online that some users of the BIOSEMI send triggers via a parallel port. Would they be using a different interface to the USB Trigger Interface? If there is a different medium for sending triggers that uses a parallel port instead, then that could also solve the problem. In the meantime, I am also seeing if the trigger software can send byte values on serial instead, but it looks unlikely.

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Gerben
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Re: Using the USB Trigger Interface as a Parallel Port

Post by Gerben » Wed Jan 08, 2020 3:51 pm

Hello Rai_aiyer,

They are most likely using the "Presentation cable", this cable connects the parallel port of the pc to the trigger input on the USB receiver.
However, please note that this cable does not emulate a parallel port but requires a real parallel port on your pc.

If you want to order this cable pleas send a email to info@biosemi.com

Best regards, Gerben (Biosemi)

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