ICP DAS USA I-7521, User Manual

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I-7521/I-7522/I-7522A/I-7523/I-7524/I-7527 User’s Manual,Ver2.5 Aug.2015
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6.1.6 Connecting multiple I-7523 modules and multiple
HP34401A
The diagram below shows how to connect a single PC to multiple
remote HP34401As on an RS-485 network. The I-7520 module is
used to convert the RS-232 signal from to PC to an RS-485 signal.
The I-
7523 module is used as an “Addressable RS-232 converter”
for the HP34401A, since there is no address setting on the
HP34401A. Two HP34401As can be connected to a single I-7523
module.
Each I-7523 module has a unique address on the RS-485 network.
Each HP34401A shares the same address range as its
corresponding I-7523 module, which allows each HP34401A to
have a unique address in this configuration.
I-7520
I-7523
RS-232
RS-485
Host PC
I-7523
HP34401A (RS-232) address=02h
HP34401A (RS-232) address=03h
HP34401A (RS-232) address=05h
HP34401A (RS-232) address=06h
RS-232
address=01h
address=04h
I-7523
HP34401A (RS-232) address=08h
HP34401A (RS-232) address=09h
address=07h
The demo program, hp23_M.c, is designed to allow a Host PC
to be linked to remote HP34401A. Refer to the companion CD for
the source code of hp23_M.c file. The key features of hp23_M.c
are as follows:

The RTS3 pin of the COM3 port on each module must first be
set as active HIGH to enable the HP34401A.