I have an old RM-1501 digital tachometer which I'm using to try to identify the speed of an object.
According to the manual I should be able to read the data over a serial link. Unfortunately, I don't appear to be able to get any sensible output from the device (never gives a valid speed). I think it might be a signalling problem because disconnecting the CTS line starts to get some data through..
Has anyone ever developed anything for one of these / had any success?
The manual does not specify that flow control is used. Open the port with hardware/software flow control disabled.
The manual does not specify the connection - whether it is DTE<->DCE or Null Modem; are you using the cable supplied with the device?
I tried every combination of hardware control (both enabled and disabled) I could think of so I think it must be a hardware problem. Removnig the CLS link between PC and the device solved the issue.
Is it actually sending data to indicate speed, or is it providing make / break on one of the pins?