
Quadrus EZ Reader User’s Manual 2-9
Communications
Multidrop
When Multidrop is selected, the protocol characters for RES, REQ, etc. are assigned
automatically.
User Defined Multidrop
Note: Any ASCII character except a null (00) and a ^A (01) can be assigned as an
address. Control characters can be used to define RES through NAK in serial commands.
Note: Definitions of commands in User Defined and User Defined Multidrop must be
duplicated in host applications to enable poll and select sequences to execute correctly
during transmission.
Note: Typically, parameters in User Defined Multidrop are defined by first enabling Mul-
tidrop, then enabling User Defined Multidrop. This pre-loads multidrop characters into
the parameters. Then changes are made to individual characters to match the host or
other requirements.
Usage:
A concentrator can be used to connect up to 50 devices to a single host
port connection.
Definition:
Multidrop allows up to 50 devices to be connected to a single RS-485 host,
with the reader assigned an unique address (from 01 to 50).
Multidrop
Addresses:
Each address has its own separate poll and select address (from 1C to 7F
hex).
Options: 01 through 50
Serial Cmd:
If selecting Multidrop (K140,5) an address must be defined and appended
to the command string.
Format: <K140,5,address>
Usage:
This option is used when connecting to a concentrator or other device that
does not match standard multidrop protocol.
If selecting User Defined Multidrop (7), complete the format by either choos-
ing new parameters or place commas where unchanged data fields occur.
Definition: User Defined Multidrop allows the user to customize the polling protocol.
Serial Cmd:
<K140,7,RES,address,REQ,EOT,STX,ETX,ACK,NAK>
For User Defined Multidrop, first select Multidrop <K140,5>, then User
Defined Multidrop <K140,7...>.
Address:
Any single character (02 hex to 7E hex) in the ASCII table can be assigned
as the address character. The character chosen is used as the poll charac-
ter and the subsequent ASCII character becomes the select character. For
example, if a ^B (02 hex) is selected as the address, ^C (03 hex) becomes
the select address that the host will use in s
ending host select commands.
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