Where is the physical location of the LAS (Link Active Scheduler)?
This is a system designer’s (and device manufacturer’s) choice. If there is a host DCS, the LAS will usually be in the fieldbus interface card. If not, it can be in a field device (but only “link master” devices offer this capability). If there is an additional back-up LAS, ready to take over in the event of failure, it could be in a separate unit, but will probably be included in a field device. This is particularly useful if the control function is executed in one of the field devices, so that the loop can work well without the host system. A valve controller is a good place to have a back-up (or only) LAS.
