RE: cRIO Profibus Module is set to communicate with MVI56 PDPMV1

[Rig]

Jesse,

In cRIO PB DP Slave  -getting started  manual in page 13 -14 /23, when or where the memory address is used .What is different between the memory address and  the index of header strurcture in page 15 /23 ?

[Jesse_D]

Hi Rig, 

That memory refers to FPGA memory. You are reading and writing responses to a place in memory. If you are unfamiliar with labview FPGA memory you can read about it the labview help. It is not a concept specific to profibus, it is a feature of labview fpga. 

The head is for your reference. If you need to parse apart responses that is the meaning of the bytes. 

[Rig]

Jesse, If I configured the profibus of cRIO PB module with software configurator II and LabVIEW successful , (1)In Request Buffer: Data of the request buffer transmitted to the c RIO PB module . Who & How write 0x82 command into index 0? Why are there an output offset in index 2-3 (2 byte) and an input offset in index 6-7 (2 byte) in the request buffer? (2) In Response Buffer: Data of the response buffer received from the c RIO PB module . Who & How write 0x82 command into index 0? Why are there an output offset in index 2-3 (2 byte) and an input offset in index 6-7 (2 byte) in the response buffer? (3)How PLC know the index X of request buffer and the index X of response buffer ? (4) If I define the output offset 100 in request buffer is motor torque data , what is in 100 input offset in request buffer ? (5) How PLC identify data of request buffer or response buffer ?

[Rig]

Jesse,

Could you answer my  questions attached  ?

[Jesse_D]

Hi Rig, 

I am going to reference the example for these questions. It is important to realize that the profibus module accessing the memory defined in addition to labview. This happens whenever you call the ReadWrite.vi

1) I have marked where the FPGA memory is written to with a 1. What you write and the offsets needed are determined by your application. What is the PLC expecting back? 

2) I have marked the where the read occurs. Once again, it is a two step process. The profibus module write to FPGA memory, then labview reads the actual values from that memory. 

3) The PLC will just see the Write input and Read output data (see 3). You are telling the profibus module where to start reading with these offsets. 

4) Whatever is returned by the PLC. The two shouldn't be correlated

5) It should be sent according to the Profibus standard, you will need to configure the data layour on the PLC side. 

I advise getting some simple data without offsets working first, then work up from there.