Rockwell Automation 2755-DM9, -DM9E High Speed Decoder - Manual (Page 26)

Chapter 3
How the Decoder Operates
3–7
will become effective immediately (except for host communications
parameters listed below). If you want to enter changes into the decoder’s
permanent memory (EEPROM), you must use the SAVE command. When
the decoder is restarted, the operating parameters of the EEPROM are
transferred into RAM. If you don’t transfer the contents of the RAM to the
EEPROM (SAVE function), any changes made to the operating configuration
stored in RAM will be erased when the power is turned off.
Note: Unlike the other decoder operating parameters, changes to the
following parameters will not take effect until you SAVE the changes and
then restart the decoder.
•
HOST PROTOCOL
•
DEVICE ADDRESS
•
ACK and NAK CHARACTERS①
•
BAUD RATE
•
NUMBER OF DATA & STOP BITS
•
PARITY
① Changes to ACK NAK characters will take effect immediately if you are in the ACK/NAK mode.
The decoder also stores the original factory set operating parameters in
EPROM. This type of memory cannot be changed by the user, and is always
available in case of a programming error. When you use a DEFAULT
command (described in next chapter), the decoder transfers the factory set
default parameters to the RAM. Once installed in RAM, the default
parameters control the operation of the decoder. If you want to save the
default parameters into the EEPROM, you must use the SAVE command.
A RECALL command (described in next chapter) transfers the previously
SAVED configuration from the EEPROM to the decoder’s RAM. Once
installed into RAM, the recalled configuration is displayed and controls
operation of the decoder.
When you configure the operation of the decoder, you will be required to
provide a variety of operating parameters. You should have an understanding
of the decoder’s operating modes prior to configuring the decoder (Chapter
4). The decoder operates in one of two modes:
•
Continuous mode - In this mode, the decoder will continuously attempt to
decode data. Use this mode for initial scan head adjustments and
positioning.
•
Triggered mode - In this mode, the decoder will only attempt to decode
data after receiving a trigger.
Operating Modes