Sullivan@cup.portal.com (sullivan - segall) (07/15/90)
My printer and my Amiga aren't talking to eachother. I've gotten
them as far as printing out data from the OS prompt, but more than
a couple of lines of text overflows the printer data buffer, and
gives me garbage.
So I checked my printer manual, and found that the printer asserts
DTR (pin 20) when it is ready to accept data, and drops DTR when
the buffer is full. I faithfully connected DTR to CTS (pin 5 on the
Amiga side) and enabled RTS/CTS handshaking from preferences.
Unfortunately in this state no data is ever sent to the printer.
So I thought I'd check the serial status bits on the serial port
to see whether the signal was coming across correctly.
I pulled out my hardware reference manual and proceeded to read about
the serial registers in the Amiga, only to find that CTS status
doesn't appear in any of them.
My questions then are these:
1. How can you perform CTS/RTS handshaking when you can't
determine the state of the CTS line? (Especially when
there isn't any hardware support for handshaking protocols.)
2. Should CTS be asserted HIGH or LOW to allow data to be
transmitted.
3. Any suggestions which might allow me to use my printer.
Additional data:
A2000, Wb1.3 (not 1.3.2), Serial TTY preferences printer,
1200 O 1 RTS/CTS, "dir >prt:"
Thanks for any help. -kls
-Sullivan Segall
_________________________________________________________________
/V\ Sullivan was the first to learn how to jump without moving.
' Is it not proper that the student should surpass the teacher?
To Quote the immortal Socrates: "I drank what?" -Sullivan
_________________________________________________________________
Mail to: ...sun!portal!cup.portal.com!Sullivan or
Sullivan@cup.portal.commcmahan@netcom.UUCP (Dave Mc Mahan) (07/18/90)
In a previous article, Sullivan@cup.portal.com (sullivan - segall) writes: > >My questions then are these: > >1. How can you perform CTS/RTS handshaking when you can't > determine the state of the CTS line? (Especially when > there isn't any hardware support for handshaking protocols.) Personally, I swear by my little LED 'blinky light tester'. They plug right inline with the RS-232 cable (assuming standard DB-25 connectors) and let you observe from the real world what is going on while the program is running. They cost about $8-$12, depending on where you get it. For those in the Silicon Valley, you can get them at Fry's Electronics (Corner of Oakmead and Lawrence Expressway in Sunnyvale) or Halted Specialties (Corner of Central Expressway and Lawrence Expressway in Santa Clara). There are other places, I'm sure. Lots of mail order places sell them, but they charge too much. >2. Should CTS be asserted HIGH or LOW to allow data to be > transmitted. It should be 'asserted'. Asserted (as I recall, but I may be wrong) means a negative voltage level WRT signal ground (pin 7). Why they made the 'asserted' state negative is beyond me, but that's the standard. Of course, your printer may think 'asserted' is positive voltage WRT signal ground, but then I guess that's why the RS stands for "recommended standard". How can a standard only be recommended. Either it is or it isn't. > -Sullivan Segall -dave