Section 4 - Read And Write Operations; Read Operations - Honeywell UDC2300 Product Manual

Section 4 – Read and Write Operations
4.1

Read Operations

Introduction
Transaction states
Analog or digital
10/00 RS422/485 ASCII Communications Option Product Manual
The Read operations (Data Retrieval) allow your computer to read data
from any controller on the RS422/485 link. Data retrieval for each
operation is accomplished through a message exchange between your
computer and the device you are addressing.
You can request the data for only one identifying code at a time, but the
response may be a single variable or a three variable type depending on
the code used.
Read transactions can be performed in either UDC state: Monitor or Slave.
Any change made in UDC state or control mode will not be indicated in the
response until the next transaction.
The parameters being read will be either Analog (codes 1 through 125) or
Digital (codes 128 through 255) value or selections so that all Read
message formats must adhere to the standardization rules shown in the
tables that follow.
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