MACH3 Plasma help please

[AndrewMawson]

I am re-vamping a plasma table that I bought from a chap who scratch built it. It all works very well, and I have re-housed his existing AM882 stepper drivers and Purelogic (Russian) Ethernet to Parallel, and BOB and torch height controller in a more robust manner - it all still works (phew!)

I have added an 'under hood' and huge downdraught fan as a direct crib of DaveK0974's design (with his permission) and now I want to control the fan via MACH3 - the BOB has three uncommitted relay outputs, one of which I've connected to drive a beefier relay to control the fan (65 cu M / Min !!!)

However I'm failing to understand the (to me) obscurities of the manual for the BOB (attached) - I'm no MACH-3 expert and would ask if anyone who has more MACH-3 experience could interpret what they are saying re: the relay outputs as there seem to be too many perms and comms for my poor old brain to understand. Ideally I want to turn the relay on when the cut starts, and turn it off a predetermined time after the cut ceases, but just to turn it on and off would be nice :)

[m_c]

It's not just you!

From what I can work out, the relays share control with the stepper controls, but SW3-5 allow you to disconnect the relays, and there is an option to use Relay3 via the coolant timer system. However I can't see anywhere that actually tells you what pins control the relays.

[Clive S]

The pins to control the relays are on page 8 in the table I have one of these bobs it take a bit of getting used to but they are good.

[AndrewMawson]

Clive, this is good news as I've not come across anyone confessing to have one !

My system is using 4 axis (as A is used as a slave) - so in simple idiot proof terms, (remembering that I've not been able to interpret that table), what do I need to do to drive one of these relays on and off from G code or otherwise ? Presumably there are links and DIP switches as far as hardware is concerned, then some set up in MACH-3 ?

I'd much appreciate your input.

[Clive S]

I'd much appreciate your input

You have said you have one relay connected is this the one you want you are having trouble with?

I have not altered my setup for some time so am a bit rusty on the BOB but I will get back to you tomorrow after I have checked it out re the pins.

[AndrewMawson]

Yes Clive just the one relay, which I can connect to any of the three relay output contacts of the BOB.

I am unclear how Mach treats these outputs. Is it by M code, do I need to write a diddy bit of code or what?