Hi, just trying to help with an answer in case you are in a hurry. It also helps me to quiz myself on applications on whether I
am right or wrong. Here is my two cents.
If I understand correctly, your temp sensor is reading 18C as verified by the PV readout, and you have your "action" temp at a set value (SV) of 23C.
You are able to program 4 alarms with this PID. The values you are using for ALM1 and ALM2 do not seem to be appropriate values for your fermentation chambers. This can easily be verified on whether or not your AL1 or AL2 (alarm indicators) are turned on when you expect them to be. If those indicators are not visible on the front panel, then something is possibly programmed incorrectly.
Now it is very possible I can be wrong here, but let us look at those values.
For ALM1 you state you have a value of 9999 and for ALM2 you state you have a value of -1999. If that is indeed the case
then this is what will happen (as I understand it - and remember, I am just a homebrewer learning to use these devices like yourself).
High Limit Alarm:
If your PV (temp sensor value) is greater than ALM1 (which you have as 9999) and add HY (which you have as 0.2) then the alarm will turn on. This means your temp sensor would have to reach 9999.2 prior to activating the alarm.
Low Limit Alarm:
If your PV (temp sensor value) is less than ALM2 (which you have as -1999) and subtract HY (which you have as 0.2) then the alarm will turn on. This means your temp sensor would have to reach -1999.2 prior to activiating the alarm.
If it were me, and I didnt want my fermentation to go below 18C, Then I might set ALM2 to be 19C and change the value of HY to be 1. This way, when my fermentation chamber drops to 18C the dry contact alarm relay would close and as long as I have my light bulb wired into the circuit correctly, It should turn on. You should also get an indication on the front panel of the PID showing the relay had activated.
Hopefully, I have explained this correctly and await the forum administrators to explain correctly. If I have misled you, I apologize beforehand.