This Article explains Precautions for Downloading to FF Devices at Plant to systems in operation.
Precautions for Downloading to FF Devices at Plant Operation
Operations Before Downloading
The following explains the operations that should be performed before downloading (predownload operation). They are necessary in order to safely perform downloading to the system currently being operated. The pre-download operation changes the AO block parameters of the Fieldbus device to be downloaded.
Be sure to perform the pre-download operation in order to perform safe downloading. If this operation is not performed, the control loop that contains the target Fieldbus device may behave in an unexpected manner.
Before Proceeding to main topic lets clear your concept with this topic Foundation Fieldbus Overview.
Before downloading, perform the pre-download operation described in steps 1 to 4 to the FF-AO block.
Step 1. Changing the FF-AO Block Mode
Change the mode of the FF-AO block to which downloading is to be performed to MAN using the Operation and Monitoring function (HIS).
When change mode of a FF faceplate block for FF-AO or similar block, it is necessary to avoid to change the faceplate block into O/S status. Generally, the mode of a faceplate block reflects the mode of the Function Block lined to the faceplate block. However, when the faceplate block becomes O/S status, the mode of the linked function block will not be reflected to the faceplate block.
Step 2. Setting the OUT Value of the FF-AO Block
Set the OUT value of the FF-AO block to the safe side. The definition of safe side differs depending on the process; check that the safe side is set correctly.
Step 3. Changing the Upper Block Mode
Change the mode of the upper block connected to the FF-AO block (e.g., a PID in the case of an FCS function block) to MAN using the Operation and Monitoring function (HIS).
Be sure to change the mode of the upper block to MAN.
If it is set to AUT and the mode downloaded to the AO block is CAS, the cascade control by the upper block is restarted immediately after the completion of downloading. For this reason, the control loop that contains the Fieldbus device may behave in an unexpected manner, depending on the output value of the upper block.
Step 4. Uploading the FF-AO Block Parameters
After downloading, upload the FF-AO block parameters in order to prevent the FF-AO block from changing the mode.
After downloading, the Fieldbus block is placed in the same mode as when it was previously uploaded. The mode may be different from at the time of downloading, depending on the condition of previous uploading.
Downloading
The updated information is downloaded to the FCS, IOM, and Fieldbus device. After the download, check the safety of the process and change the block mode of the FF-AO block, etc. as needed.
If online downloading to the fieldbus device failed, offline download to the device may become necessary. In this case, choose [AdvancedFunctions] – [Initial download] to start download.
Offline Download (Master Data Download)
After downloading with [Advanced Functions] – [Master data download…], the fieldbus block will be in the previously uploaded mode.
The mode may be different from the mode during downloading depending on the status of the previous uploading.
Following topics are related to this topics and more understand about foundation fieldbus.
What Is Fieldbus Engineering? Technical Approach
Number of Fieldbus Devices Connected per Segment of Fieldbus