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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6.1.4 Connecting multiple I-7522 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 the PC to an RS485 signal.
The I-
7522 module is used as an “Addressable RS232 converter”
for the HP34401A, since there is no address setting on the
HP34401A.
Each I-7522 module has a unique address on the RS485 network.
Each HP34401A shares the same address-range as its
corresponding I-7522 module, which allows each HP34401A to
have a unique address in this configuration.
I-7520
I-7522
RS-232
RS-485
Host PC
HP 34401A (RS-232)
#2
HP 34401A (RS-232)
#4
HP 34401A (RS-232)
#6
I-7522 I-7522 #1
#5
#3
The demo program, hp22_m.c, is designed to allow a Host PC
to be linked to a remote HP34401A. Refer to the companion CD
for the source code of the hp22_m.c file. The key features of
hp22_m.c are as follows:

The configuration of the COM port on the I-7522 module is as
follows:
COM2 (485) COM3 (232)
Baud Rate 9600 (default) 9600 (default)
Parity None (default) Even
Data 8 (default) 7
Stop-bit 1 (default) 2

The RTS3 pin of the COM3 port on each module must first be
set as active HIGH to enable the HP34401A.