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TD 200 Parameters and Messages
D.5
Understanding Message Types
Every message falls into one of four possible message acknowledgement and editing types.
This section explains specifically how each message type is handled by the TD 200. The
four message types follow:
No acknowledgement required. No edits allowed.
Acknowledgement required. No edits allowed.
No acknowledgement required. Edits allowed.
Acknowledgement required. Edits allowed.
No Acknowledgement, No Edits Allowed
In this combination of no acknowledgement required and no edits allowed, the TD 200
simply displays the message. The ENTER key has no function since there are no editable
variables within the message. The message can contain variables that are updated at the
update rate of the TD 200. This type of message is replaced on the display if a higher priority
message is enabled by the S7-200 CPU. The operator can either press the UP or the DOWN
arrow key to scroll through other messages or press ESC to return to the Menu mode.
The TD 200 does not clear the corresponding message-enable bit in the S7-200 CPU.
Acknowledgement, No Edits Allowed
In this combination of acknowledgement required and no edits allowed, the TD 200 displays
the message and makes the entire message flash (blink) until the operator presses ENTER
to acknowledge the message. Variable values are updated from the S7-200 CPU at the
normal update rate while the message is flashing.
When the operator presses ENTER, the TD 200:
Sets the acknowledgement-notification bit in the first format byte of the message.
Clears the message-enable bit for this particular message. This causes the message to
be removed from the display on the next update cycle.
Another message cannot replace the one flashing until the operator acknowledges the
flashing message. This is also true even if a higher priority message is enabled in the S7-200
CPU. If the TD 200 is configured for 20-character messages and the CPU enables a higher
priority message, the flashing message shifts to the second line of the display. The operator
cannot press the UP or the DOWN key to scroll through other enabled messages until s/he
acknowledges the current message.
No Acknowledgement, Edits Allowed
In this combination of no acknowledgement required and edits allowed, the TD 200 displays
a message and then waits for the operator to edit it. All of the variables within the message
are updated at the update rate. Since the message does not require acknowledgement, this
type of message is removed from the TD 200 display if a higher priority message is enabled
in the S7-200 CPU. An up or down arrow in the right-most character position indicates more
messages. The operator can press either the UP or the DOWN arrow key to scroll through
the other enabled messages.
For more information about editing variables, see Section D.6.
D-20
SIMATIC TD 200 Operator Interface
C79000-G7076-C205-04
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