GE VersaPoint IC220PBI002 User Manual page 126

8
Request and Response Format
The format for all types of access (Request and Response, Read and Write) in
DP/V1 is:
<DP/V1 header> <Data (PCP/DP/V1)>
The format of the DP/V1 header is always:
<DP/V1 service> <Slot> <DP/V1 index> <DP/V1 length>
The <Data (PCP/DP/V1)> is optional depending on the service. It has the following
structure:
Access
Write objects
(NIU)
Read objects
(NIU)
Write objects
(I/O modules)
Read objects
(I/O modules)
Write objects
with Invoke ID
Read objects
with Invoke ID
In the event of a faulty response, the format is:
▪
For a DP/V1 error:
<DP/V1 service> <Error decode> <Error code 1> <Error code 2>
1. For an I/O module error:
<DP_V1 service> <Slot> <DP_V1 index> <DP_V1 length> <Error data (PCP_DP_V1)>
8-6 VersaPoint™ I/O System Profibus-DP NIU User's Manual – August 2005
Service
Request
Response
Request
Response
Write request (Write)
Write response (Write)
Read request (Write)
Read response (Write)
Write request (Read)
Write response (Read)
Read request (Read)
Read response (Read)
Write request (Write)
Write response (Write)
Read request (Write)
Read response (Write)
Write request (Read)
Write response (Read)
Read request (Read)
Read response (Read)
Data
Object data
None
None
Object data
Write PCP/Index high/Index low/Subindex/Length of PCP
data/x bytes of PCP object data
None
None
PCP acknowledgment
Read PCP/Index high/Index low/Subindex
None
None
PCP acknowledgment
Invoke ID/Write PCP/Reserved/Reserved/ Reserved/
Reserved/Index high/Index low/ Reserved/Subindex/
Reserved/Length of PCP data/x bytes of PCP object data
None
None
Invoke ID (mirrored)/Write PCP/ Reserved/ Reserved
Invoke ID/Read PCP/Reserved/Reserved/ Reserved/
Reserved/Index high/Index low/ Reserved/Subindex
None
None
Invoke ID (mirrored)/Read PCP/Reserved/ Reserved/
Reserved/Length of PCP data/
x bytes of PCP object data
GFK-1911B