Hey folks,

I'm doing an extension to my project on reading data from devices. I'm using a simple while loop with DBInputParams and separate DBOutputParams to store results.

In a while loop I have my function (readDeviceParams) utilizing RDREC standard function which iterates over all config in DBInputParams (HW_ID, ParamLength) reaching next device with each iteration.

I found that some devices may be added to my function if I will use RDREC/WRREC standard functions to read data asynchronically. 

I did realize I cannot use asynchro communication unless I will hold WHILE loop till I get parameters read from device and assign them to DBOutputParams. Otherwise my results will not be stored for a correct device. Am I right that asynchro communication should be handled in a case-state machine approach? Wait for .DONE, store values, proceed with next drive...

Would it be feasible to run RDREC/WRREC in While ... Loop?

Thanks, R

Gustavo Antonio Banchetti Brucatori

1. Yes, you are right;
2. No. don't use the while loop with any asyncronous POUs.

Is it possible to use one function call of RDREC/WRREC with different set of input parameters?

Lets say, I'm reading same parameter value from same type of device but I have 25 of them in the network with different HW_ID (of course).

Simplified code:

Case status:

0: WRREC (HW_ID[x],....) // Write request paramter from device x

NOT BUSY and DONE

status:=1

1: RDREC (HW_ID[x],....) //Read requested parameter from device x

NOT BUSY AND VALID //evaluate execution status of RDREC

Value of device [x] := RECORD; //store requested parameter value

status:=2

2: ///go to next device

x := x+1;

status:= 0 // start over with next device

Yes, it's possible to use the same instance for subsequent sessions with different parameters.

Is it possible to use one function call of RDREC/WRREC with different set of input parameters?

 Glad to hear. Do you have any examples to share? 

jacek d

Yes, it's possible to use the same instance for subsequent sessions with different parameters.

Is it possible to use one function call of RDREC/WRREC with different set of input parameters?