Keenso REX-C100FK02-M*AN Temperature Controller, 0-400C, PID Self-Identification, 250V AC

For the price, this is a very nice device. The quality of the plastic case is not as good as the high end units, but it will do the job. It does not include ramping and timing features like the high end ones, so if you just need a simple controller that does the PID calculation, this is a good option. It also has one of the best PID autotune functions I have seen, however, use caution with low thermal mass systems that have quick heating times as the overshoot can be quite high during the tuning process. You can autotune at a lower temperature to compensate for this. The only issue I see with the device is in the set mode, the digits flicker rapidly rather than blink. This makes setting in high light levels somewhat annoying.The unit is quite easy to disassemble, and is quite easy to modify. I converted a few from a relay output to a DC output to drive an external SSR by removing the internal relay, and populating 2 jumpers on the board that there are convenient traces and holes for.Some of the other reviews here are negative, the stated reason that it will not drive an external SSR. These reviews are most likely a user problem: I think they are incorrect reviews as this part number device has relay contacts as the output. It is not intended to directly drive an SSR.

I returned

Documentation is sparse and cryptic but I was able to decode it eventually and got fine results. The device is now serving quite well as controller of a small high-temp (1100C/2000F) oven.

This product did not send a signal to active a solid state relay (output was 0V) when temperature was below set point.