For those of you out there that are using the RKE or RKL to control/monitor you tank, there are some new things happening at DA that you may be interested in. They have three new modules that are being worked on. One of them, the DC1, is now shipping. The DC1 works in tandem with the APC module which is a pump controller. The DC1 allows the APC to also control any of the DC pumps such as the Diablo 5500.
The second module is the DP1 which is a programmable dosing pump. They have built prototypes and they have been tested on a system with 16 pumps attached and everything works great. It will probably be a couple of months before the DP1 is released.
The third module, the SLX, is just like an SL1 or SL2 with 2 switch inputs, temp input, and ph. It also has a 2nd port that can be switched between ORP and ph, depending on what you want.
I imagine a firmware update will be forthcoming very soon to provide support and compatibility with these new modules. They are using Facebook to announce these releases so look them up there for more info.