What is the difference between discharge, auto discharge and OK to discharge?

The discharge, auto discharge and OK to discharge parameters on the HI 3010 are confusing. When would I use one discharge type over another discharge?

On the HI 3010, DISCHARGE is a signal that the cycle is complete and the material needs to be moved.  This would normally require a signal from the operator or PLC to start the discharge operation.  The DISCHARGE signal can come from an input that could be manual or automated from another process.

There are three parameters that would deal with the discharge: 
Discharge
Auto Discharge
OK to Discharge

Discharge defines if you will have a discharge state.  If you have Discharge turned off, then the unit will skip the discharge state.  This means that at the end of a cycle, it will go directly to the start of the next cycle.  Normally, you would not have this set to off unless you are doing single cycles.  If you are doing multiple cycles, it will go directly to the start of the next cycle and start filling the same container again.  Having a discharge allows the container to be removed and a new, empty container to be placed in position to be filled.

AUTO DISCHARGE defines if the unit will automatically start the discharge, or if it needs to wait for a discharge command.  It is only valid if you have discharge set to on.  If auto discharge is on, then the unit will automatically go into the discharge mode.  If it is off, the unit will indicate it is waiting for a discharge command before continuing.

The OK TO DISCHARGE is an input from another phase of the process that says they are ready for the discharge to occur. This could be an input from an operator or another process. If you have OK to Discharge ON, the discharge cannot happen until this signal is present.  This could be a signal from a PLC or one of the inputs on the unit, depending on how it is mapped.  If the OK to Discharge is OFF, then the unit can go into discharge mode as soon as it gets the signal to based on the Discharge and Auto Discharge parameter settings.

You can use a combination of the OK TO DISCHARGE and the AUTO DISCHARGE to control a cycle.

The discharge signal, ok to discharge, and discharge command, if needed, would all be mapped signals using either the inputs from some communications input like a PLC, or to the digital inputs on the unit.  The Discharge signal would need to be mapped to a relay output or out over communications to another device that would handle the actual discharge signal.