control disks individually

[HARD_DRIVEN]

Is there any way to control disks individually? To have one power down while the others run?

[hdsentinel]

No, there is no way to control disks individually.

But this is not required at all: when any of the disks are in sleep / standby, Hard Disk Sentinel does not access them.
Just make sure that the periodic detection should happen LESS frequently than the disk standby timeout.

For example, if you configure hard disks to spin down after 30 minutes, then you should set the detection frequency in Hard Disk Sentinel to detect status only once per hour (at Configuration -> Advanced options page, move the slider to right). Otherwise the periodic detection (like any read command) may prevent entering to sleep/standby.

Please note that some configurations (motherboard, chipset, drivers, USB enclosure, etc.) may not provide the actual power state correctly. Then you can enable the option "Automatic detection based on disk utilization" option too on Configuration -> Advanced options page below the slider also. This way Hard Disk Sentinel will not only check the power state of the drive (which may not 100% correct in all cases) but also checks if there was data transfer (read/write) since last detection.

[HARD_DRIVEN]

But this is not required at all

I require it. One of my disks overheats very quickly . It is an external which sits on tower and sata connects. I need to be able to stop it when finished with it. It is too much to have to plug out each time

[ZaP]

Why not have a fan on it?

I have a four bay dock full of HDD and have a desktop USB fan blowing air across it all the time. Keep in mind the heat rises and the heat in your tower could be contributing to the overheating.