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TD 200 Parameters and Messages
Defining the Data Value Format
Figure D-10 shows the bit values of Byte 0 and Byte 1 of the format word. Byte 0 uses only
five bits (bits 0 through 4). Byte 1 uses only six bits (bits 0, 1, 2, and 4, 5, 6). All other bits of
the byte (for both Byte 0 and Byte 1) must be set to zero.
Byte 0
MSB
E – Edit Allowed
P – Password Protected
EN – Edit-Notification
Byte 1
Figure D-10 Bit Values of the Format Word
Do not use non-printable characters in your message text: the TD 200 uses these characters
to identify the start of a format word. The non-printable characters are ASCII codes 0 to 31 (0
to 1F hexadecimal).
Acknowledgement Bit 0
To ensure that important messages are displayed and acknowledged by an operator, you
can program a message to require acknowledgement. You do this by setting the
acknowledgement bit in the most significant byte of the format word. Figure D-11 shows the
placement of the acknowledgement bit in byte 0 of the format word.
MSB
7 6
0
Figure D-11 Acknowledgement Bit of Byte 0 of the Format Word
D-12
Format Word
Byte 0
Byte 1
Byte 2
MSB of
LSB of
MSB of
Format
Format
Data
LSB
7 6
5
4 3
2
1
0
0
0
E P EN
AN
A
A – Acknowledgement
AN – Acknowledgement-Notification
Format Word
Byte 0
Byte 1
Byte 2
MSB of
LSB of
MSB of
Format
Format
Data
MSB
LSB
7 6
5
4 3
2
1
0
0
S S 0
D
D
D
Format Word
Byte 0
Byte 1
Byte 2
MSB of
LSB of
MSB of
Format
Format
Data
LSB
5
4
3
2
1
0
0
E P EN
AN
A
Optional Data Value
Byte 3
Byte 4
Byte 5
LSB of
Data
Optional Data Value
Byte 3
Byte 4
Byte 5
LSB of
Data
D – Placement of the Decimal Point
S – Data Size/Format
Optional Data Value
Byte 3
Byte 4
Byte 5
LSB of
Data
A – Acknowledgement
0 – No acknowledgement
1 – Acknowledgement required
SIMATIC TD 200 Operator Interface
C79000-G7076-C205-04
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