ICP DAS USA I-7521 User Manual page 137

Application 4: Addressable RS-232 Controller (Three channels)
 Each I-7523 module has a unique address
 Each I-7523 module can support three RS-232 devices, AA, AA+1 and
AA+2
 The Host PC first sends a command to all I-7523 module
 The destination I-7523 module will pass the command to its local
RS-232 device 1, RS-232 device 2 or RS-232 device 3.
 The I-7523 module then sends the response from the RS-232 device
back to the Host PC
 COM4 port of the I-7523 module can support either 1 or 2 stop bits, so it
can support a two stop-bit device, such as the HP34401A.

The RS-232 device can be used for command (Application 1) or null
command (Application 2) type controller applications
 Refer to the 7523.c file for the source code of the firmware
I-7521/I-7522/I-7522A/I-7523/I-7524/I-7527 User's Manual,Ver2.5 Aug.2015
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