Skip to main content

Commands and confirmation

A command is a value that YTCC writes to a field device, for example a start command or a new setpoint. Every command passes through the YTCC server, which checks it before the driver sends it to the device. Buttons and inputs on a screen only start the request; the decision is made on the server.

Confirmation before sending​

Before a value goes to the field, the runtime screen asks for confirmation in a Command confirmation window. The window shows the description of the signal, or its full path when it has no description, and asks Send the command? Cancel is the default button; the command is sent only when you click Send.

An event script that runs after an operator action asks in the same way. These writes do not ask:

  • Writes to internal signals, which do not go to the field.
  • Writes made by page scripts, which run without an operator.
  • A Write Tag action with Confirmation dialog (off: the popup itself is the confirmation) turned off. Use it for a button in a command popup that already is the question. Only the window is skipped: sign-in, the stale-data block, the reason and second user of critical commands, the write limits and the command log stay.

Critical commands​

A signal can be set to require more for its commands:

  • Reason: the user must type a reason of up to 500 characters.
  • Reason and second user: in addition, a second user with the Approve commands (four eyes) permission must approve the command. The second user cannot be the same person, and the approval is valid for 5 minutes.

When user login is off for the project, only the reason is required.

When a command is refused​

The server refuses a command in these cases:

  • The user does not have the Field writes permission.
  • The signal is in Manual [SCADA] or Simulated mode. See Operating mode.
  • The signal belongs to an area of responsibility that another user controls.
  • There is no communication with the driver or the device. The command is not stored to be sent later.
  • A command to the same signal is still in progress.
  • The value is outside the write limits of the signal, or, for a signal of type enum, not one of the values of its enum type, such as 1 and 2 of a double command. For an enum signal the driver never receives such a value, and write limits do not change it.
  • The command is more than 2 seconds old when it reaches the driver. This prevents a delayed command from acting long after the operator gave it.

Command result​

The operator sees the result of each command:

ResultMeaning
Command appliedThe device accepted the command.
Command applied and confirmedThe device accepted it and the read-back value matches.
Command sent (no device confirmation)The command was sent, but the device does not confirm commands. Shown as a warning.
Command result not receivedNo result came back in time. By default YTCC waits 10 seconds; the time can be set per signal.
Command could not be verifiedThe read-back value did not reach the expected value.
Command rejectedThe command was refused. The reason follows the text, for example No device communication or Previous command in progress.