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Figure D-6 shows a referenced byte (MBn) and shows which bit of the byte is set by each
function key.
Warning
!
The TD 200 sets an M bit each time a function key is pressed. If you do not intend to use
function keys, and therefore do not assign an M byte address for function keys, the TD 200
defaults to byte M0 for the function keys. If your program uses bits in M0, and a user
presses any function key, the TD 200 sets the corresponding bit in M0, overwriting the
value assigned to that bit by your program.
Inadvertent changes to M bits could cause your program to behave unexpectedly.
Unpredictable controller operation could cause death or serious injury to personnel, and/or
damage to equipment.
Always reserve an M area address, even when your program does not utilize function
keys.
Figure D-6 Bits Set by Each Function Key
Message Address Bytes 6 and 7
Bytes 6 and 7 of the TD 200 parameter block define an integer-word offset in V memory
where the TD 200 looks for the first message. Valid offset values for specific CPUs are
defined in the SIMATIC S7-200 Programmable Controller System Manual .
Note
Each 20-character message uses 20 VB memory locations; each 40-character message
uses 40 VB memory locations.
Message-Enable Address Bytes 8 and 9
Bytes 8 and 9 of the TD 200 parameter block define the integer-word offset in V memory
where the TD 200 looks for the first byte of the message-enable bits. Valid offset values for
specific CPUs are defined in the SIMATIC S7-200 Programmable Controller System Manual .
For example: if you assign VB50 as the message-enable address, the first message is
enabled by bit V50.7, the second message by V50.6, the third message by V50.5, and the
eighth message by V50.0.
SIMATIC TD 200 Operator Interface
C79000-G7076-C205-04
M Area Address
Byte 5
0
1
2
3
4
Offset
MSB
7
6
5
4
Shift
Shift
Shift
Shift
MBn
F4
F3
F2
F1
TD 200 Parameters and Messages
6
7
8
9
M
LSB
0
3
2
1
F4
F3
F2
F1
D-7
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