Rockwell Automation 2706 DL20 SERIES G USER MANUAL - Manual (Page 17)

Chapter 2
Introduction to the DL20
2–3
Addressable Master
The addressable master feature allows you to connect 100 DL20s to a single
RS-422 port on the controller. Each display has its own unique address. The
controller can command any one, or all of the DL20s on the network to
display a message.
Slave Mode Master
The DL20 can operate as a slave device. In run mode, special commands
place the DL20 into slave mode. As a slave device, the DL20 does not
respond to message triggers, but displays strings of ASCII text sent by
the controller.
Programmable Controller Interface
The host controller can trigger a message display using either:
•
Parallel Data Lines
The DL20 has ten data lines and two strobe lines which accept DC input
voltages from 5 to 30 volts.
The optional Parallel Input Converters (Catalog No. 2706-NG1, -NG2)
allow the DL20 to accept 120VAC input signals. The logic program
in the controller turns some lines ON and some OFF. The DL20
recognizes this combination as a message number.
!
ATTENTION: Parallel Input Converters (Catalog No.
2706-NG1, -NG2) cannot accept 220/240VAC. If 220/240VAC is
applied to the Parallel Input Converter, damage to the input
converter will occur.
•
RS-422 / RS-232 Serial Ports
Both the RS-232 and RS-422 ports accept serial commands and variable
message data. The serial commands are formatted and recognized
identically to the parallel commands. The only difference between the
two is the wiring of the signals and the host controller program.
Host and Slave Devices