@Phaedrux
To establish Z0 I have been pre-heating then home all axis and then posn. nozzle at bed centre. I then inched my Z down to 0.1mm from bed and then reset Z=0. I then raised the nozzle 5mm and deployed my IR probe. I read the resultant Z offset and put this figure into my z probe offset in config.g. I then performed a mesh compensation action. After as a check I again positioned my nozzle at the bed centre and jogged down until Z = 0 and checked nozzle bed clearance. It has never been 0.1 as set, so I have to adjust the z offset to get my desired 0.1. I think the probe is reflecting off the glass bed bottom face, I have tried using black paper as a backing but my glass bed slides about on it. So I have used heat sink double sided tape and set my mesh grid to probe 4 corners. I also discovered that any mechanical clearance in my hot end linear bearings etc can influence the IR probe results. I have reduced any play in my hot end transport and things are now much better. I will try G30 as you suggest. I was a total newbie to configuring G code . My knowledge was limited to start and end code in Marlin for slicing.

@Phaedrux I forgot to say that I removed the optical Z stop and just used the IR sensor. I found that if I used the optical end stop and Z probe I was getting a large Z offset on my mesh map. I could reduce the offset by adjusting the height of my optical Z stop. Now I use the mesh map as reference to adjust my bed manually and once level I then adjust my Z probe offset in my config.g.

@T3P3Tony
Thanks Tony, I have just had an email from Ooznest and they have instructed me to send package details for the to arrange collection. I am very impressed with the Duet board but have found the set up instructions a mine field because they cover a selection of boards. I have been viewing this forum for setup info along with YouTube. I had a problem with trying to use my IR probe to home Z because I was using an optical end stop as well. There was another guy had the same problem and it was pointed out he was using an end stop as well. There was no resolve. I did this and it works fine: M574 Z1 S2 ; set Z limit switch

Z-Probe
M558 P1 Z1 C"zprobe.in" H5 F200 T5000 R0 ;set Z probe type to switch and the dive

@T3P3Tony
Initially I wanted to purchase the board from Duet direct but was directed to a reseller. If I get this sorted out I am thinking of buying another for my Anet printer. I will try again to purchase from Duet direct because of their warranty policy, that I did not know of at the time of purchase. Otherwise it would have to be a clone from China and lose £70 and not £144.

@droftarts
I have been using the same USB lead that I have used with my Serial Tools and BOSSA to initially connect to my computer (iMac) and it has been working fine. I have had the board connected to my printer and had just got the IR probe configured and working. I had done some test prints using PETG but was getting bed adhesion problems, so was trying different adhesives on the bed. I did a complete install of the Duet Combined firmware using BOSSA and verified ok but the diagnosis LED will not go out and the heater LED remains dimly lit.

@T3P3Tony
I had the board powered from my Wanhao psu 24v and using the 5v EN configuration. It has been working fine until this morning when I noticed the bed was getting extremely hot and I tried to shut the heater down usingI thought by resetting the board it would be okay but finished up with the diagnosis LED permanently on.

@Veti

Hi Veti

I have attached 2 photos 1: U3 and 2: showing LEDs

@Veti I am a bit annoyed because I purchased a genuine Duet wi fi board thinking it would carry a warranty unlike the cheap cloned versions I could buy from China. Apparently not Ooznest have directed me to this forum and also Duet will not proceed a warranty claim because I purchased it from a reseller.

@Modelman said in Duet wifi board bed heater not switching off:

Just tried another usb cable and get the same . Diagnosis LED illuminated and the heater LED dimly illuminated

I have disconnected all other connections from the board.

Just tried another usb cable and get the same . Diagnosis LED illuminated and the heater LED dimly illuminated