AB PID startup sequence with bumpless transfer

Hello- Looking for suggestions on a PID startup sequence with bumpless transfer. Basically I need to force and hold the output to different values when the machine is warming up. Once warm, it switches bumplessly to run mode and PID control. I've seen it done a few ways-
One is to put the PID in manual during warmup and move the values in. Once out of warmup, just switch the PID to auto.
2nd is to use the PID Inhold bit and Inhold value to manually move values in warmup mode. Once out of warmup, you just release the Inhold bit. I know this PID function is originally designed for use with a 1756 analog module on startup, but it really provides the function were looking to do.

Any other suggestions or feedback on these methods? Thanks.

http://www.plctalk.net/qanda/showthread.php?t=46822

http://www.plctalk.net/qanda/showthread.php?t=76690

The above threads may help you out.
Regards,

According to the PID documentation, the second method (Inhold manipulation) is intended for bumpless start-up after a Program-to-Run Mode transition.

Its description contains the statement, "The controller’s output will ramp to the currently held output value by making use of the .BIAS term. This ramping is similar to auto bumpless transfer."

I'm not sure what they mean by "ramping." A software-initiated auto-mode transfer (i.e., unlatching the SWM bit) will step the output to the current .SO value. However, it will use the integral term (if enabled) instead of the .BIAS value (unless P-only).

It sounds like the Inhold method works when the analog output is manipulated directly, rather than through the .SO register in manual. This might be a watch-out if you are copying from a program that currently works with this method, and change to the typical manual-to-auto bumpless transfer (.SWM/.SO).

Also, in addition to handling a potential output bump, look at process variable tracking (.PVT) as one way to handle a bump from set point error just after the manual-to-auto transition.