PROFIBUS offers the following services for data transmission:
Service |
Function |
DP-V0 |
DP-V1 |
DP-V2 |
FMS |
Send Data with No acknowledge |
X |
X |
X |
X |
|
Send Data with Acknowledge |
(X) |
|
|
X |
|
Send and Request Data |
X |
X |
X |
X |
|
Cyclic Send and Request Data |
|
|
|
X |
|
Send and Request Data with Multicast Reply |
|
|
X |
|
|
Clock Synchronization |
|
X |
X |
|
These services are always requested by one bus user as the "initiator" and delivered by another user as the "responder". Only a master with the authority to transmit can request a service listed in this table, but all services can be delivered by either master or slave.
Apart from SDN and CS, services are based on a true two-way connection between initiator and responder, requiring a reaction of acknowledgment or response to all services. This important behaviour for the real-time activity of the bus system is called: immediate response.
Asking for a service is called a request (req). Confirmation of a service call is called a confirm (con). A service is displayed as an indication (ind) and optionally acknowledged as a response (res).