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If you have more than one format word in a message because you have more than one
embedded value in the message, you only need to set the acknowledge bit in the first format
word of the message. The TD 200 ignores the acknowledge bit in all subsequent format
words of the message.
When a message requiring acknowledgement is enabled for display:
The TD 200 displays the message and causes it to flash.
The message is not removed or replaced on the TD 200 display, and continues to flash,
until the operator acknowledges it by pressing ENTER.
The TD 200 sets the acknowledge-notification bit and removes the message after the
operator presses ENTER.
See Section D.5 for more information about how the TD 200 processes messages with
acknowledgement.
Acknowledge-Notification Bit 1
The S7-200 CPU program uses the acknowledge-notification bit to note that the operator has
seen and acknowledged a message. To acknowledge a message,
1. Move the cursor to the display line requiring acknowledgement and
2. Press ENTER.
After the operator presses ENTER, the TD 200 sets the acknowledge-notification bit. The
S7-200 program uses the acknowledge-notification bit to note that the operator has
acknowledged the message. You must design your S7-200 program to reset this bit if you
want subsequent notification. Figure D-12 shows the acknowledge-notification bit, located in
byte 0 of the format word.
MSB
7 6
0
Figure D-12 Acknowledge-Notification Bit of Byte 0 of the Format Word
SIMATIC TD 200 Operator Interface
C79000-G7076-C205-04
Format Word
Byte 0
Byte 1
Byte 2
MSB of
LSB of
MSB of
Format
Format
Data
LSB
5
4
3
2
1
0
A N – Acknowledge-Notification
0
E P EN
AN
A
0 – Not acknowledged
1 – Message Acknowledged
TD 200 Parameters and Messages
Optional Data Value
Byte 3
Byte 4
Byte 5
LSB of
Data
D-13
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