Version for antique levers

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Nearly all retractable/extendable operant chamber levers on the market are controlled by a single (output, from the computer's point of view) line. When the line is on (1), the lever extends and stays extended for as long as this control line is on. When the lever is off (0), it retracts. In addition, there is a response (input) line: 1 = lever depressed, 0 = lever not depressed.

 

However, some old (1980s?) levers from Campden Instruments, which are easily recognized because they require mains voltage (in the UK, 240 V AC) - and therefore require considerable respect when installing and handling them! - operate differently. They have the following control system (Julie Gill and David Maul, Campden Instruments, personal communication, June 2008):

 

•each lever has a response line (input): 1 = lever depressed, 0 = lever not depressed
•there is also a lever position line (input): 1 = lever retracted, 0 = lever extended
•and there is a lever motor line (output): this is normally held at 0, but a 40-100ms pulse to 1 (and then back to 0) latches the lever motor on. If the lever was extended, this pulse causes it to retract; if it was retracted, the pulse causes it to extend.

 

The SimpleSchedules_AntiqueLevers.exe program is a separate executable from the usual SimpleSchedules.exe program, and it supports these old levers. In all other respects it is identical to the main task. The required devices (q.v.) are slightly different; this is deliberate, so you can't accidentally run the wrong version of the task and not notice. There is also a message on the main window to announce the fact that you are using the "antique levers" version.

 

The program does not support the levers in a very sophisticated way, but as follows:

•Whenever the program wishes the levers to change state, it checks the current state by asking the lever. If the current state is what the computer thought it was, then it pulses the motor to change the state. If it wasn't, then the lever isn't working properly; it flags this on screen and in the text log file (and doesn't pulse the motor, since the lever is already in the target state).