1dharvey@teknowledge-vaxc.ARPA (Doug Harvey) (04/29/88)
I just received the following message when trying to redirect output to COM1 (which is connected via null-modem to a Sun workstation): c:\> echo logon > com1 [enter] Write fault error writing device COM1 Abort, Retry, Ignore, Fail? I'm using DOS 3.3 on a highly IBM compatible clone. It doesn't complain when I issue the same command to COM2, (an internal modem not connected to anything at the time). I tried rebooting but that didn't help...also tried setting the port with MODE but no luck either. The DOS manual doesn't list this error message. I've this before on an IBM PC/AT with no problems at all, using COM2 (without using the MODE command). The line is configured (on the Sun, anyway) at 9600 baud, and it works great when using Crosstalk or Kermit 2.3. Any help appreciated, Doug
jcmorris@mitre-bedford.ARPA (Joseph C. Morris) (05/02/88)
In a recent article Doug Harvey writes: >I just received the following message when trying to redirect >output to COM1 (which is connected via null-modem to a Sun >workstation): > > c:\> echo logon > com1 [enter] > > Write fault error writing device COM1 > Abort, Retry, Ignore, Fail? [...] >The line is configured (on the Sun, anyway) at 9600 baud, and it >works great when using Crosstalk or Kermit 2.3. Check your null modem cable. I would suspect that it fails to provide at least one of the DSR, DCD, and CTS leads. KERMIT will cheerfully transmit into a dead connector, but it's possible that DOS will not. I don't know if CROSSTALK requires that the leads be asserted, but if it's like most comm programs it will ignore them. Try strapping the null modem so that DTR (Data Terminal Ready) on each end drives DSR (Data Set Ready), DCD (Data Carrier Detect, also sometimes called Received Signal Level Detect or RSLD), and CTS (Clear to Send) on the other end of the cable. In pinouts, that's saying that pin 20 on one end of the null modem cable should be connected to pins 5, 6, and 8 on the other end. An alternative strapping preferred by some systems (just to confuse matters) drives each end's CTS from its own RTS lead, and drives each end's DSR and DCD from the opposite DTR. Strap 4 and 5 together in each plug, then strap 20 on one end to 6 and 8 on the other. Good luck.
del@Data-IO.COM (Erik Lindberg) (05/06/88)
In article <22210@teknowledge-vaxc.ARPA> 1dharvey@teknowledge-vaxc.ARPA (Doug Harvey) writes: > c:\> echo logon > com1 [enter] > > Write fault error writing device COM1 > Abort, Retry, Ignore, Fail? The PC initializes the COM port to expect full handshake. You can change the COM port initialization, as mentioned in another article, or you can make a cable that supplies the appropriate signals. Assuming you only want a 3 wire connections, and don't want to pay for the extra wires in your cable, make the following connections at the PC end of the cable: Connect pins 4&5 together. Connect pins 5,8 and 20 together. This will satisfy the UART and allow communications. You didn't have any trouble with the internal modem because it is, of course, designed to work with the PC internal BIOS. -- del (Erik Lindberg) uw-beaver!tikal!pilchuck!del
keithe@tekgvs.TEK.COM (Keith Ericson) (05/14/88)
In article <884@pilchuck.Data-IO.COM> del@pilchuck.Data-IO.COM (Erik Lindberg) writes:
<make the
<following connections at the PC end of the cable:
<
<Connect pins 4&5 together.
<Connect pins 5,8 and 20 together.
^
<
I'm pretty sure he meant 6,8 and 20...
keith