HMS A8NDPV1 Instruction Manual page 114

TIA Portal Acyclic communication example
It will now be possible to reference the inputs and outputs of the function block instances, mak-
ing it easier to create the program. Proceed to prepare the sequence. Add a new network in the
user program that will start the state machine sequence. Setting ParameterRequest will start the
state machine from state 1, initialize all used variables (readStatus, readValue, writeStatus), copy
the requested PNU from tag requestedPNU to the data structure, and trigger the write request (by
setting the REQ input of the WRREC function block).
The BUSY output of WRREC will immediately turn ON. Once it turns OFF, proceed to reading the
result of the write request (state 2).
Expect to see either output DONE or ERROR of WRREC in an ON state. If DONE is ON, the write re-
quest was performed successfully, reset the REQ input, and proceed to creating the read request
(state 3). If the ERROR output is ON, check the STATUS output to read the error. If the status is equal
to 0xDE80B500, the result is not yet ready. In this case, do nothing and wait for the actual result.
In every other case, save the status to tag writeStatus and enter state 10, indicating that a write
request error occurred.
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Doc.Id. HMSI-216-127
Doc.Rev. 1.01