YASKAWA PROFIBUS-DP 1000 Series Technical Manual page 26

7 Option Data and I/O Maps
Example of Handshaking
Clear the handshaking register HS bit (bit 7) to 0 for the PLC program after turning on the power supply or after re-
initializing. Figure 12 describes the handshaking function. The arrows indicate whether the PROFIBUS-DP master or
the option has the control for the protocol.
Figure 12
Synchronize Command Bits
to Start the Message Process
Create
Command
Signal New
Message Waiting
Create
Command
Signal New
Message Waiting
Create
Command
Signal New
Message Waiting
26
PROFIBUS-DP Master
Handshaking Output Register
0
⇓
0
⇓
1
1
1
⇓
1
⇓
0
0
0
⇓
0
⇓
1
Figure 12 Example of Handshaking
SI-P3 Card
Handshaking Input Register
0
0
⇒
0
⇓
0
⇓
1
1
⇒
1
⇓
1
⇓
0
0
⇒
0
⇓
etc.
YASKAWA ELECTRIC SIEP C730600 42B 1000-Series Option SI-P3 Technical Manual
Synchronize command bits
to start the message process
New MEMOBUS/Modbus
Command to SI-P3 Card
Command Executed
Response Valid
New MEMOBUS/Modbus
Command to SI-P3 Card
Command Executed
Response Valid
New MEMOBUS/Modbus
Command to SI-P3 Card