Programming the Local Host
Chapter 5
516
Notice the format used in the read and update immediate:
/
G
G
G
G
/
The format is: get the data and put it here.
Read
Update
G
G
/
/
G
G
Examine Start Bit
Assign a unique start bit to each command rung. The start bits are
examined by the PLC-2/DHII interface. When you turn on the start bit,
the PLC-2/DHII interface carries out the programmed command.
Assign a unique start bit to each immediate-access update rung and each
command rung. Use the ladder-diagram program to turn on the start bit
whenever and as often as your application requires.
Control the start bit through your ladder diagram program. Turn it on
when you want to send the command message to the remote node.
Programming methods for start-bit control are covered in the discussion
on “Controlling the Start Bit,” following Figure 5.15.
The module controls certain data table words specified by the programmer
in the local station processor. These data table words indicate the status of
command execution and provide various types of diagnostic information
for start-up and troubleshooting. These words are:
One or more pairs of adjacent words for start/done and remote/local
fault storage.
An error word.
Status Words
