Uncommunicative 634


New member

I've been trying to make an RS232 CFA-634 communicate with my Mac via a keyspan USB->RS232 converter with little success for a while. Today I decided to rule out the Mac and the keyspan and grabbed a VT-220 and a Windows laptop from work. Using the same keyspan and cable I can talk just fine between the Mac and the VT, the PC and the Mac and the PC -> VT. I did all the comms at 19200/8/N/1, no flow control as this is how I have my 634 set.

No matter what I do I don't get a single character on the 634 (except when plugging the rs232 in while the unit is on, after using it between the other machines, some stuff left in the buffers?).

I have a 5vDC power adapter running to the +LCD, +LED and GROUND pins of J2, and an off-the=shelf RS232 cable on the DB9. The display doesn' t seem to operate at all without the J2 power connected (I thought it would operate without the backlight). Once I attach the J2 power, I get the boot screen (which confirms the 19.2k baud rate) then a flashing black cursor. No text though, no matter what port settings or what I send.

Perhaps there is some problem with the cable? Do I need to do the JPC/JPD close to make the thing be ready to receive?

I'm sure I'm doing something dumb here, so any help gratefully received.


-- Chris
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CF Tech

My first guess would be the cable. It must be a "straight through" cable, not a "null-modem". You can check by making sure pin 2 goes to pin 2.

The Radio Shack 26-152 works (and may be available locally), as well as our own WR232Y01.
USB LCD Displays - Graphic and Character LCDs with a Keypad