Process Image; Determine The Size Of A Slot For Data Transfer In The Master - WAGO I/O-SYSTEM 750 Manual

116 • Appendix
Mailbox Command References

6.3.4 Process Image

6.3.4.1 Determine the Size of a Slot for Data Transfer in the Master Process Image
(SetRemotePiSize, 0x32)
With this command, the process image of a remote bus module is limited to n
bytes within the master process image. Therefore, the total of all slave process
images in the master may not be larger than the set master process image - 2.
This is because two bytes of the total size are necessary for the control/status
byte and a reserved byte. The size of the master process image can be queried
and configured over the parameter channel. It is contained in the LSB by pa-
rameter 0.
By downsizing the available process image, the sum of the configured cutoffs
may exceed the size of the master process image. In this case, the initial con-
figuration is already invalid. In such a case, the configuration is executed, but
the error value MBX_CMD_INVALID_CONFIGURATION is displayed. If
the initial configuration is correct, a command that leads to an invalid configu-
ration is acknowledged and rejected with an error.
Note
The process image mapping can also be configured in the slave mode, but
does not have any effect until it is changed to the master mode.
Note
Slots 1 and 13 must be given as parameters in the area 0 through 12.
Conditions
Request
Byte
Mailbox size Operating mode/profile
6 12 18 Config.
● ● ●
7 6 5
2 2 2
0 MBX_SETREMOTEPISIZE
1 T
2 MBX_TARGET_TABLE_AND_INDEX
3 CUTOFF_N_BYTES
Real-
Ad hoc
time
● - -
4 3 2
2 2 2
-
Device role
Save
config.
Master Slave
● ● ●
1 0
2 2
WAGO-I/O-SYSTEM 750
Restart
-
I/O Modules