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Rockwell Automation 2706 DL20 SERIES G USER MANUAL User Manual

Page 109

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Chapter 8
Special Functions

8–21

Selecting a Master Address

The addressable master option allows you to connect up to 32 DL20s on a
single RS-422 network (up to 100 with inline repeaters). You can trigger
messages at one or all of the DL20s by sending a master address with the
message number. Refer to Chapter 5 for a description of addressable master
protocol.

The prompt for setting a MASTER ADDRESS looks like this:

SET MASTER ADDR? N

If you answer Yes to this prompt, the DL20 will display:

MASTER ADDRESS: 0

You can now enter the master address. Some values are illegal addresses,
Table 8.D lists them:

Table 8.D
Illegal Master Addresses

Decimal

Hex

ASCII Character

4

04

EOT (CTRL D)

6

06

ACK (CTRL F)

7

07

BEL (CTRL G)

13

0D

CR

18

12

DC2 (CTRL R)

20

14

DC4 (CTRL T)

22

16

SYN (CTRL V)

43

2B

+

45

2D

-

48 through 57

30 through 39

0 through 9

A master address of 0 disables the master address feature.

Note: Address 127 is recognized by all masters, regardless of the master
address. Use this a convenient means of triggering a message to all master
displays.

Note: A master address can also be selected using the Addressing Bar
(Catalog No. 2706-NF1) at the parallel port. This method does not require a
keyboard or terminal and is useful if you are downloading messages from a
tape. The Addressing Bar can only be used if communication to the display
is through the serial port.