Specifications

Technical Specifications Appendix A
441
Status Information
There are 50 bytes of special memory (SM) allocated to each intelligent module based on its
physical position. The module updates the SM locations corresponding to the modules’ relative
position to the CPU (with respect to other modules). If it is the first module, it updates SMB200
through SMB249. If it is the second module, it updates SMB250 through SMB299, and so on. See
Table A-41.
Table A-41 Special Memory Bytes SMB200 to SMB549
Special Memory Bytes SMB200 to SMB549
Intelligent
Module in
Slot 0
Intelligent
Module in
Slot 1
Intelligent
Module in
Slot 2
Intelligent
Module in
Slot 3
Intelligent
Module in
Slot 4
Intelligent
Module in
Slot 5
Intelligent
Module in
Slot 6
SMB200 to
SMB249
SMB250 to
SMB299
SMB300 to
SMB349
SMB350 to
SMB399
SMB400 to
SMB449
SMB450 to
SMB499
SMB500 to
SMB549
These SM locations show default values if DP communications have not been established with a
master. After a master has written parameters and I/O configuration to the EM 277
PROFIBUS--DP module, these SM locations show the configuration set by the DP master. You
should check the protocol status byte (for example SMB224 for slot 0) to be sure that the EM 277
is currently in data exchange mode with the master before using the information in the SM
locations shown in Table A-42, or data in the V memory buffer.
Tip
You cannot configure the EM 277 PROFIBUS--DP I/O buffer sizes or buffer location by writing to
SM memory locations. Only the DP master can configure the EM 277 PROFIBUS--DP module
for DP operation.
Table A-42 Special Memory Bytes for the EM 277 PROFIBUS--DP
Intelligent
Module in
Slot 0
... Intelligent
Module in
Slot 6
Description
SMB200 to
SMB215
... SMB500 to
SMB515
Module name (16 ASCII characters)
“EM277 ProfibusDP”
SMB216 to
SMB219
... SMB516 to
SMB519
S/W revision number (4 ASCII characters)
xxxx
SMW220 ... SMW520 Error code
16#0000 No error
16#0001 No user power
16#0002 to 16#FFFF Reserved
SMB222 ... SMB522 DP slave module’s station address as set by address switches (0 -- 99 decimal)
SMB223 ... SMB523 Reserved
SMB224 ... SMB524 DP standard protocol status byte
S1 S0 DP Standard status byte description
0 0 DP communications not initiated since power on
0 1 Configuration/parameterization error detected
1 0 Currently in data exchange mode
1 1 Dropped out of data exchange mode
S0
00000
MSB LSB
0S1
SMB225 ... SMB525 DP standard protocol -- address of the slave’s master (0 to 126)
SMW226 ... SMW526 DP standard protocol -- V memory address of the output buffer as an offset from VB0.
SMB228 ... SMB528 DP standard protocol -- number of bytes of output data
SMB229 ... SMB529 DP standard protocol -- number of bytes of input data
SMB230 to
SMB249
... SMB530 to
SMB549
Reserved -- cleared on power up
Note: SM locations are updated each time the DP slave module accepts configuration/ parameterization information. These
locations are updated even if a configuration/parameterization error is detected. The locations are cleared on each
power up.