Andrew Grimberg wrote:
Greetings folks,
Am I just blind or can I not find what type of null modem cable that I
need for heartbeat? I've got several full-handshake cables that while I
can communicate in one direction, aren't working in the opposite
direction. Anybody got a suggestion as to what type of null modem cable
I should be using?
-Andy-
Here are my notes:
P: Error:
heartbeat[2830]: 2007/06/26_13:27:06 WARN: glib: TTY write timeout
on [/dev/ttyS0] (no connection or bad cable? [see documentation])
heartbeat[2830]: 2007/06/26_13:27:06 info: glib: See
http://linux-ha.org/FAQ#TTYtimeout for details
Prints repeatedly in the ha.log file even when both nodes are up. You
can manually send data over the null modem cable.
NOTE: Seeing this error once when one node is down is normal!
S: As per the referenced URL; The null modem cable you are using most
likely does NOT have the CTS and RTS lines connected (pins 7<->8).
You will need to verify this using a continuity tester. The needed
cable pinouts are:
CD - 1 ---------\ /--------- 1 - Carrier Detect
RD/RX - 2 ---------|----\/----|--------- 2 - Receive Data
TD/TX - 3 ---------|----/\----|--------- 3 - Transmit Data
+----------|--------- 4 - Data Terminal Ready
DTR - 4 ---------|----------+
CG - 5 ---------|----------|--------- 5 - Common Ground
DSR - 6 ---------/ \--------- 6 - Data Set Ready
RTS - 7 --------------\/-------------- 7 - Request To Send
CTS - 8 --------------/\-------------- 8 - Clear To Send
RI - 9 -] [- 9 - Ring Indicator (not
used/no connection)
In case my ASCII art confuses you, tie pins 1 and 6 together and run
them to pin 4 on the other side of each. So I could have drawn the above
diagram like this (Same thing just expressed differently):
CD - 1 -\
DSR - 6 --+--------------------------- 4 - DTR
RD/RX - 2 ------------------------------ 3 - TD/TX
TD/TX - 3 ------------------------------ 2 - RD/RX
DTR - 4 ---------------------------+-- 6 - DSR
\- 1 - CD
CG - 5 ------------------------------ 5 - CG
RTS - 7 ------------------------------ 8 - CTS
CTS - 8 ------------------------------ 7 - RTS
RI - 9 -] [- 9 - RI (not used/no
connection)
Lastly, there is no wiring colour code. If you are making your own
cables, make your own colour code too!
HTH!
Madi
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