Allen-Bradley A-B QUALITY DL20 Series User Manual page 72

Control F is a flash code. If you want flashing characters, send a control F
with the 20 character packet. Every character on the specified line will flash.
A second control F cancels flash mode.
Control R is the reset command. After receiving a control R within the 20
character packet, all the data registers in the DL20 are cleared. For example,
if you were to send 10 characters, then a control R, you could then send 20
more characters followed by the slave address, followed by the line number,
followed by a carriage return. The 20 characters that you sent would be
displayed on the appropriate DL20. The ten characters sent before the
control R would be lost. Control R also resets the flash status to nonflash.
Important: Send a control R to all DL20s when the host controller powers
up, because when a serial port powers up it may inadvertently transmit
erroneous data.
Slave Mode Baud Rate
The current address and baud rate are displayed on power up. The baud rate
of the DL20s must match the baud rate of the host controller. There are three
baud rates: 300, 1200, and 9600 baud. Generally, any of these can be used.
However, it is possible that some host devices could be programmed to
transmit too many characters too fast at 9600 baud. If you do find a problem,
change the rate to 1200 baud, as most users have found that to be an
acceptable rate.
Slave Mode Individual Relay Control
Turn off relays in individual slave displays on an RS-422 network by sending
the command sequence:
[Slave Address] [Line Number] [Return]
Line number 48 (ASCII 0) turns the relay on and line number 49 (ASCII 1)
turns the relay off. One possible use for this feature is to signal an incoming
message by connecting a bell or light to the relay.
ATTENTION: The relay must only be used for the annunciator,
not control functions.
!
Chapter 6
The Serial Port
6–7