ShockJocky
Member
Upon replacing a 120V prox I find that the PLC doesn't sink enough current to operate the prox. Is there a simple solution?
prox to a plc
- Thread starter ShockJocky
- Start date
rsdoran
Lifetime Supporting Member
I do not understand the problem.
Always go to the source. This is one of the most important troubleshooting tips.
When working with electricity you basically have 2 things, a power source and a load, this is true in every aspect.
In this situation you have a prox going to a plc input, what is the prox? It is a power source. The plc input is the load i.e. the prox signal energizes the plc input led and associated code.
Here is the key to electrical components, the load device (plc input in this case) will need a certain amount of current to operate, the prox in this case is the power source and must be able to provide that current. The plc input will have nothing to do with the ability of the prox's operation, just the opposite, the prox must provide a signal that the plc can use.
BTW sink and source are dc related terms and not used with 120vac.
Always go to the source. This is one of the most important troubleshooting tips.
When working with electricity you basically have 2 things, a power source and a load, this is true in every aspect.
In this situation you have a prox going to a plc input, what is the prox? It is a power source. The plc input is the load i.e. the prox signal energizes the plc input led and associated code.
Here is the key to electrical components, the load device (plc input in this case) will need a certain amount of current to operate, the prox in this case is the power source and must be able to provide that current. The plc input will have nothing to do with the ability of the prox's operation, just the opposite, the prox must provide a signal that the plc can use.
BTW sink and source are dc related terms and not used with 120vac.
Last edited:
ShockJocky
Member
OP
Correct on the sink source, should have said "draw". The prox won't enable the input. But when same prox is connected to a small cube relay it will close the relay. the prox has a rating of 5mA-300mA.
rsdoran
Lifetime Supporting Member
CroCop said:
I agree that something else is wrong, try connecting power direct to the input to verify it is working.
ShockJocky
Member
OP
The input lights when I jump 120v directly to it. also see the states on my laptop change
ShockJocky
Member
OP
Idec SmartRelay FL1C-H12RCC The specs book lists no input impedance
Just checked it myself.
It states that the input current at signal "1" is >0.08 mA.
So there you have it, the prox is incompatible with the PLC.
Easiest workaround is via a relay like you suggest yourself.
edit: See page 270.
http://www.idec.de/produkte/support/handbuecher/sps/SmartRelay/Englisch/SmartRelay%20FL1C%20Manual%20B827-0.pdf#search=%22Idec%20SmartRelay%20FL1C-H12RCC%20spec%22
It states that the input current at signal "1" is >0.08 mA.
So there you have it, the prox is incompatible with the PLC.
Easiest workaround is via a relay like you suggest yourself.
edit: See page 270.
http://www.idec.de/produkte/support/handbuecher/sps/SmartRelay/Englisch/SmartRelay%20FL1C%20Manual%20B827-0.pdf#search=%22Idec%20SmartRelay%20FL1C-H12RCC%20spec%22
Last edited:
ShockJocky
Member
OP
Lists nothing for input current
rsdoran
Lifetime Supporting Member
JesperMP said:
The prox rating stated 5ma to 300ma, if that is what it can output to the plc then that would be greater than .08ma. I guess the key would be if that is the power rating for the prox and what is the actual output rating of the prox.
It may be incompatible but usually if it can trigger an electromechanical relay then a plc input should be nothing.
Just a thought, you do have the neutral for the 120vac connected to the inputs?
Money4Nothing
Member
rsdoran said:
This is likely your problem with the AC inputs. The neutral is not properly referenced to the common on the I/O terminals.
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rsdoran
Lifetime Supporting Member
I found the manual too: http://www.idec.com/us/productsupport/P_ManualsList/WindLGC/FL1C_Manual5_04.pdf
It appears that the H12RCC model does not have a separate connection for the input neutral. There is a note that the input signals, per group i.e. inputs 1-4, must be from the same phase. In other words if you have 240vac with a neutral then the 120vac for each group of 4 inputs must be from the same phase.
The specs for the turning on/off the input is on page 34. The voltage must 79 or over with greater than .08ma for a signal of 1, and less than 40v and less than .03ma for a signal of 0.
It appears that the H12RCC model does not have a separate connection for the input neutral. There is a note that the input signals, per group i.e. inputs 1-4, must be from the same phase. In other words if you have 240vac with a neutral then the 120vac for each group of 4 inputs must be from the same phase.
The specs for the turning on/off the input is on page 34. The voltage must 79 or over with greater than .08ma for a signal of 1, and less than 40v and less than .03ma for a signal of 0.
Last edited:
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