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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Chapter 1 Introduction
Nowadays, a great number of RS-232 devices for both automation
and information transfer are being used in industrial applications, and
linking these devices is very important in the modern situation. The
devices are usually located at a distance from the Host PC, meaning
that linking via multiple serial cards is inefficient. ICPDAS I-752N
series products have been developed to provide an effective link
between multiple RS-232 devices via a single RS-485 network. This
network protocol offers stability, reliability and simple cabling while
delivering a low
–cost, easy-to-maintain product.
1.1.
Overview
Addressable RS-232 Converter
Most RS-
232 devices don’t support individual device addressing. To
overcome this limitation, ICPDAS I-752N series modules assign a
unique address to any RS-232 device installed on an RS-485 network.
When the Host PC sends a command to the RS-485 network a device
address can be attached to the command. The destination I-752N
module will then remove the address field and pass the remaining
commands to the destination RS-232 device. Responses from the
local RS-232 devices will be returned to the Host PC via the I-752N
module.
Responses from RS-232 devices can be addressable
ICPADS I-752N series modules can prefix a response from an RS-232
device with a unique address and then pass the response to the
RS-485 network. The Host PC can then identify which RS-232 device
the response comes from.
Master-type Addressable RS-232 Converter