There are several instances where it may be necessary to operate multiple 1401s in the same experimental setup. For example, more waveform input channels may be needed when running the Spike2 software, than are available with a single, fully expanded 1401. The synchronising option lets the user link several 1401 systems to overcome this problem.
Linking separate systems raises the issue of timing. When used independently, each 1401 can be started with the same trigger pulse, but then runs at a clock rate derived from its own internal crystal clock.
The accuracy of the internal clock is 50 parts per million or better over time and operating temperature. This means that two 1401s started with the same start pulse could be up to 1 second different after 6 hours. For many applications, this may not be significant, but for experimental procedures where multiple 1401s are in use, it may make it difficult to line up events that had been recorded by different 1401s.
To address this problem, the Power1401 and the Micro1401-3 and 2 have factory-fitted options to synchronise multiple 1401s so that their crystal clocks keep exactly in step.
When fitted, the synchronising option adds a rear-panel connector into which a daisy-chain cable plugs. The wiring in the cable determines which 1401 has the "master" clock and which are "slave" units. A slave 1401 detects an incoming clock signal and measures its frequency. If it is satisfied that the external signal is an acceptable clock, it will switch its reference clock to use the external frequency instead of an internal crystal. This process is automatic and requires no intervention from the software. The clock signal is regenerated in each 1401 to pass on to the next unit. Cable lengths can be up to 2 metres between 1401s.
The number of 1401s that may be synchronised in this way is 3 or 4, determined by the cabling. To cater for synchronising more 1401s, CED plans to introduce an external synchronising box that will act as a "master" and produce clocks for up to 8 "slaves". This unit will also have facilities for locking to user-supplied external frequency sources such as DAT machines and video genlocks.
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CED, through this site, does two things that relate to privacy. We would like to explain them.
We offer free down-loads of many files on our site, from test programs to complete install files for updated versions of major packages like Spike2 and Signal.
When customers wish to take a down-load of a major package, we ask a few questions, including their name, email address, the serial number of the software for which they seek an upgrade and whether they would like an automatic email whenever we update the product. This information is emailed back to CED when they access the final down-load screen. Within this email, your browser transmits the type and version of browser you are using, and the screen resolution you are running.
The reasons why we take and keep this information are that it is useful for our software development team to know who has taken the latest versions, and it is useful for our web site development team to know which browsers people are using to view our site, and what resolution they have their screens set to.
When people down-load a major package, we try to write a cookie, a small file in your computer, that records your name, serial number of the software package, and the version you are down-loading. These files have a lifetime of one year.
The reasons for storing this information are firstly that if you ask for another down-load some other time, your details are read from the cookie and are pre-written into the form, to save you looking them up again. The other reason is that next time you access our site, your browser looks through your CED cookies and compares the versions down-loaded with the latest version numbers read from our site. If there is a later version of a product you have already down-loaded, we tell you on the home page screen, so you know that it is worth going to the down-load page again.
None of this information is ever given to anyone outside CED. ×