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We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?

We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?

Just some additional input to my earlier reply, Barry : The 4-20mA transmitter is normally powered by a 24v DC source ( PLC, DCS etc) which contains a 250 ohm resistor across the input terminals. This resistor converts the current ( 4-20mA) int a Voltage signal ( 1-5 V) as the input to the PLC, DCS etc..

So in the overall loop, one needs to add this resistance to that of all other devices in the loop, to obtain the total loop resistance.

We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?

Thanks, I think I understand now how it works. The sensor itself will send 4-20ma regardless of IP voltage provided it has enough voltage to push through the impedance of the connected components.

Just some additional input to my earlier reply, Barry : The 4-20mA transmitter is normally powered by a 24v DC source ( PLC, DCS etc) which contains a 250 ohm resistor across the input terminals. This resistor converts the current ( 4-20mA) int a Voltage signal ( 1-5 V) as the input to the PLC, DCS etc..

So in the overall loop, one needs to add this resistance to that of all other devices in the loop, to obtain the total loop resistance.

We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?

That's correct. 

The transmitter being powered with 24v DC, will cause a current, representative of the Process Measured variable  to flow in the complete circuit.

There is one possible problem that could occur here : If the 24v DC supply is lower than normal, and the resistance is close to the total limit of 750 ohms, there may not be sufficient Voltage force for the current to flow; in this case, the reading on the receiver ( PLC or DCS) will be lower than the true value.

All of the above parameters are easily verified with a Digital Multimeter in the case of suspected error.

Hope this helps.

Kind regards,

Charles

Thanks, I think I understand now how it works. The sensor itself will send 4-20ma regardless of IP voltage provided it has enough voltage to push through the impedance of the connected components.

Just some additional input to my earlier reply, Barry : The 4-20mA transmitter is normally powered by a 24v DC source ( PLC, DCS etc) which contains a 250 ohm resistor across the input terminals. This resistor converts the current ( 4-20mA) int a Voltage signal ( 1-5 V) as the input to the PLC, DCS etc..

So in the overall loop, one needs to add this resistance to that of all other devices in the loop, to obtain the total loop resistance.

We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?

We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?

What Bluetooth receiver are you using?

We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?

Erbessd 4-20mA

Bluetooth 4-20mA Sensor

ERBESSD INSTRUMENTS		remove preview
Bluetooth 4-20mA Sensor EPH-G61 is a Bluetooth 4-20mA sensor. Monitor output of any 4-20mA transducer. Ideal for LVDT, pressure and level sensors. Modbus Protocol available View this on ERBESSD INSTRUMENTS >

What Bluetooth receiver are you using?

We are retrofitting a 4-20 ma system to remove the circular paper chart recorder and install a Bluetooth receiver for the 4-20 signal.

 The Bluetooth receiver is designed to take a 4-20 ma input and send it through the internet to the cloud

Other than setting the receiver 4-20  0 (4 ma and max 20 ma max) are there other considerations ie the impedance of the current leg?

Is it possible to put the new receiver and the current system in series? Will it require any different calibration?