4230/4232/4235 Communications modules
8-9
its own. This introduces a delay of 4 character transmission times in
the branch (approximately 4ms at 9600 baud).
Using a leased-line and modems to operate the system
across sites
Computer
4232 (addrs 0)
Controller
d/s 485
4230 C/M
u/s
232
u/s 485
Controller
4232 (addrs 1)
Controller Controller
u/s
485
d/s
232
d/s
485
Controller Controller
u/s
RS232
d/s
RS485
Modem
Modem
Controller
4232 (type E)
Telephone
line
In this layout, the 4232 Comms modules on each side of the modem
perform RS485/RS232 conversion and baud rate conversion. One of
the 4232 Comms modules is set to type E so it adds nothing to the
messages. Set the downstream DIR/DIAL link on JU3 of the Comms
module at the host end of the telephone line to DIAL to increase the
time-out on the line. (If the branch is really slow then you can set the
A/B link on JU3 to B, but this will only work if the Controller
addresses are from 00 to 09.)
Note that the telephone line used between the modems must be
permanently connected (leased-line).
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