Calling a cicode function from a page event doesn't work at times

Two possible causes I can think of right now:
1. If no user is logged in when opening the page, the tag cannot be written to (standard security feature).
2. The statements take too long (blocking) and the event is aborted while not finished. To overcome this you can put the statements in a cicode function and then call that function from the event using TaskNew().

Hi Patrick, for No.1 when user is logged out, can this be allowed to run cicode when a user is logged out? I need a heartbeat to PLC running always to let the PLC know the client is online.

Running cicode will work when no user is logged in, but writing tags will not.

To overcome this, there are a few options. I will list them in order of security (least secure at bottom):

1. Create a mechanism on a server component (report server for example) that will check for online clients and set variables accordingly. This is the most secure, but also the most difficult solution.

2. Create a dummy Role and User with no privileges and areas. On every Client, create a startup cicode script that will log in this user by default. Also make sure you create an alternative logout function as well that logs in this dummy user instead of logging out. This will allow clients to write to tags while "logged out".

3. From the client call a function on a server component using RPC (ServerRPC / MsgRPC). The server function will write to the variable. For this you have to set "Allow RPC" to TRUE in configuration of the server component. Also, you have to create and use the dummy user and role descibed in option 2, and set "Allow RPC" to TRUE for this dummy Role as well.

When you say 'know the client is online', what do you mean? Do you have multiple PlantSCADA clients and the PLC needs to keep track of each one of them?

Or, do you just have one Plant SCADA PC that is both a server and client? If that's the case, then as long as you are running in Multi-Process mode (selected in the Setup Wizard), you can just define an event that toggles your heartbeat bit. Then run the Setup Wizard and enable that event to run on the I/O Server process. The server processes by default have full privileges, even if no user is logged in to the client process.

This screenshot is from the Power edition of Plant SCADA, but it's the same thing. Also, I like to name the event according to the PC or process where it should be run. You can have multiple events with the same name (it's really like a group name). It makes it a lot easier in the future when someone is running the wizard and may not be familiar with the events and what should run where.

When you say 'know the client is online', what do you mean? Do you have multiple PlantSCADA clients and the PLC needs to keep track of each one of them?

Or, do you just have one Plant SCADA PC that is both a server and client? If that's the case, then as long as you are running in Multi-Process mode (selected in the Setup Wizard), you can just define an event that toggles your heartbeat bit. Then run the Setup Wizard and enable that event to run on the I/O Server process. The server processes by default have full privileges, even if no user is logged in to the client process.

This screenshot is from the Power edition of Plant SCADA, but it's the same thing. Also, I like to name the event according to the PC or process where it should be run. You can have multiple events with the same name (it's really like a group name). It makes it a lot easier in the future when someone is running the wizard and may not be familiar with the events and what should run where.