ABB AC 31 Technical Manual page 171

Page 6-18
Program Optimization
The variables OWxx.00 and Iwxx.07 on the master and IW00.00 and OW00.07 on the slave
are reserved for the dataflow control between the central units.
- Total number of data to transmit between the master and slave central unit
- Memory address of the first data to transmit or the memory address of the first
variable to receive the first data. The memory address list can be found in the annex.
The MR_CS31(master) and ST_CS31(slave) function blocks are used for a data transfer from
the slave central unit to the master central unit (see Figure 6-12).
MR _CS31
D AT A
IW xx.06
IW xx.00
IW xx.07
H andshake
O W xx.00
Figure 6-12 : Data transfer from the slave to the master
The following information is required for these blocks:
- The slave number.
- The number of words to use per exchange : a data table may be transmitted over the
CS 31 bus 7 words by 7 words or, 6 words by 6 words or, 5 words by 5 words, etc. It is
therefore possible to use the unused words for a rapid data transfer between central
units at each CS 31 bus cycle. The data transfer may therefore be carried out with 2
different time bases. A typical application is the transfer of parameters from the CS 31
master to the slave 4 words by 4 words, the 3 remaining words being reserved for the
rapid transfer of the inputs/outputs. The available outputs on the slave are OW00.06,
OW00.05, etc. and the corresponding inputs on the master are IWxx.06, IWxx.05, etc.
This number should be identical for both functions.
The variables OWxx.00 and IWxx.07 on the master and IW00.00 and OW00.07 on the slave
are reserved for the dataflow control between the 2 central units.
- Total number of data to transmit between the master and slave central unit
- Memory address of the first data to transmit or the memory address of the first
variable to receive the first data. The memory address list can be found in the annex
The function blocks for the data exchange master/slave and slave/master may be used at the
same time by the same program.
S T_C S 31
D AT A
O W 00.0
6
O W 00.0
O W 00.07
IW 00.00
ABB Control - AC 31
1SBC 260400 R1001-b 06.99