# Tying FM200 systems into SCADA 2.0



## Lone Crapshooter (Nov 8, 2008)

This is a repost from last night that I accidently posted in the wrong place.

I am looking at tying 5 FM200 systems into to a plant wide SCADA system.
Each FM200 system has it's own stand alone control panel and there is wiring between the FM200 control panels and a PLC located in the protected areas.
My knowledge of PLC's is very limited but I do know they have 4-20 mA analog inputs. Each FM 200 system would have it's own analog input card.

I am suggesting using a 4-20mA input card (powered from the PLC) to monitor the status of the FM200 systems. The FM200 control panels have programmable relays that I can put resistors in series with the contacts for different current values.

4mA system normal
+6 mA 10 mA first alarm
+6 mA 16 mA second alarm
+4 mA 20mA system discharge

There is going be some additional programming to compensate if the system would be in trouble I think would be having windows instead of hard setpoints for the alarms and discharge but i think that would be workable.

Thanks for your help
LC


----------



## splatz (May 23, 2015)

I think 4-20ma is great but it's probably needlessly complicated here. If you just use the relay outputs for contact closure, you could read them on four digital inputs on the PLC. The programming will be simpler on the PLC, maintenance and troubleshooting will be a breeze if it's digital.


----------



## just the cowboy (Sep 4, 2013)

If you are trying to avoid pulling wire and adding hardware yes what you say will work if only one relay will be on at a time. If more than one relay pulls in decoding would be a PITA.
I would use totals of 4-7-11-18 ma That way if two get turned on or stuck on they do not equal the sum of any other.

Cowboy


----------



## micromind (Aug 11, 2007)

Be careful with 4-20ma, if both are pushing power, there'll be a fight but not for long........

One system needs to push power, the other needs to have a resistance of 250 Ohms or thereabouts.


----------



## Lone Crapshooter (Nov 8, 2008)

I want to thank everyone for their input . Now I do realize that my idea does have some credibility.
Thanks again 
LC


----------



## gpop (May 14, 2018)

Adding resistors in series using the on board relays might be more complicated than it seems. Adding then in parallel would be a easier configuration. 

What type of wire do you have between the control panel and the plc. Also is there any network capability's on the control panel?


----------



## splatz (May 23, 2015)

OK so I was playing with this, it's kind of an interesting puzzle. Just curious if that is what you were thinking of @Lone Crapshooter ... 

If I follow you're putting resistors in series like below. The R0 value sets the maximum current. The values you use for the R1, R2, and R3 are interesting. 

Your normal conditions are 

SW1-SW2-SW3
OFF-OFF-OFF Normal
ON -OFF-OFF 1st Alarm
ON -ON -OFF 2nd Alarm
ON -ON -ON System Discharge

Any other condition would indicate something's not right with the monitoring. 

I figured you'd want to choose the resistances so they are far enough apart that you're not relying on the resistors and wiring to be perfect to tell what's going on. 

Tinkering with values the best I could come up with was 

R0 = 1200
R1 = 1100
R2 = 600
R3 = 300

If the resistances are perfect, that gives you at least .78 ma between values of all the possible combinations, which isn't much. You could set ranges for conditions like so 

SW1-SW2-SW3
OFF-OFF-OFF 20ma +/- 0.5 Normal 
ON -OFF-OFF 10.4ma +/- 0.5 1st Alarm
ON -ON -OFF 8.28ma +/- 0.5 2nd Alarm
ON -ON -ON 7.5ma +/- 0.5 System Discharge


----------

