Hi Everyone
throught my learning about Master/Slave configurations
ex1:
I have a master 314 C-2 DP CPU and Profibus DP master system(dashed line),then drag and drop IM 152-1 set it as slave then add it's i/O modules,in this case the master CPU have direct access to the slave inputs/outputs
ex2:
I have a master 314 C-2 DP CPU and Profibus DP master system(dashed line),another 314 C-2 DP is set as a slave cpu,
the maste cpu doesn't have direct acces to the slave I/O so a memory area is defined as shown in pic 1

(address=4/length=2/unit=bytes),does't mean that the memory area have start address=4 and a length =2 bytes so it's (4.5),so if i have 16 sensors the length would be 2 if i have 24 sensors the length would be 3 in case of digital sensors,and what does consistency means,depending on what we set those parametres
ex3:
I have a master 314 C-2 DP CPU and Profibus DP master system(dashed line),and 313c connected with CP 342-5 to serve as slave,pic2

what's the meaning of 2bytesDI/consistency unit ,is't 16 bits of input memory (the memory which the master CPU read from),if he (313c connected with CP 342-5 ) station have SM modules how will the master reads from them
am confused with the presence of CP module
pease correct me if am wrong

kind regardes

 

This must be a fairly recent innovation by Siemens as I have not heard of master / slave relationship between CPU's and I/O modules.

Historically and especially the S5 series processors, I/O was fixed addressing in 'bytes' so one 16way i/p module would take up 2 addresses. This has continued with the S7 series.
I'm guessing 'consistency' is a modern description for status, as module status is reported back to the CPU but doesn't take up address memory.

 

The profibus master will not have direct access to signal modules on the profibus slave. The slave will write to a Q area and the master will read an I area and vice versa for opposite data flow, IO areas configured in profibus parameters. You will need PLC code to copy signal module data to Q area.
Consistency refers to how much data is read as a group, e.g. if you are reading a 16 bit integer you would want to read it with word consistency.