Analog input signal

Hello all
I have problem with level sensor which causes trip for pumps
Unfortunately now we don't have access to plc
How make this sensor send constant value for the plc for example 10 mA to avoid trip for pumps as a temporary solution

Use a mA simulator set for 10 mA. Some multimeters have this capability. You will need to know if the PLC provides the power for the loop or if the level sensor provides the power to choose the correct “simulator” function (usually referred to as “simulate” and “source”, respectively).
Thx for reply
So will i keep the simulator on during all this period for example one week till find solution ... You know it works on battery

Appreciate your help
Be aware that a battery powered 4-20mA calibrator is likely to power off after some time that there's no 'knob' activity (to save the battery).

Several thoughts on substituting something to get 10mA of loop current.

1. I have a couple cheap-o 4-20mA sources/simulators whose indicated mA value is not dead-nuts on, but they work for simulating multiple analogs where accuracy is not important. The cheap-o's will run continuously until the battery runs down. I use a cell back-up power pack and they easily run all day.

2. A backup cell phone power pack (lithium battery) with a 250 Ohm resistor (assuming the PLC analog input resistance is 250 Ohms) in series with the analog input. Those charger packs run at 5V, so you need 500 Ohm to get a current 10mA, 250 Ohms from the analog input, 250 Ohms from the series resistor. The 5000mAHr pack should last a couple weeks. You'll have to cut and wire a USB cable for connections.

3. Some transmitters can be put into a force mode that drives the loop current to a specified value. The intended use is for loop testing. Sometimes the values are fixed, 4, 12 & 20mA. Many times there's a means to specifiy a value. I have never used this feature for more than a couple minutes with any field transmitter, so I don't know if the forced loop current will hold indefinitely or if the mode times out after some period of time, (like a battery powered loop calibrator).

Words to use to search a manual to see if a force function is available.

constant current mode
Loop Test

4. Transmitter Failsafe mode
All smart transmitter have a failsafe mode that drives current up-scale or down-scale when the transmitter brain detects that it can't make a reasonable measurement. Sometimes there are "hold last value" or "fail at xx.x mA" choices. Beyond whether a fail at xx.xmA is available or not, the overall problem with failsafe is simulating a failsafe condition with a working transmitter. But maybe your transmitter is in failsafe mode.

5. Even the inexpensive benchtop DC variable power supplies typically provide an Amps digital readout to three decimal places, so you could get a 0.010A output from one. If you use a variable power supply, start at a very low voltage and work your way up slowly. Too much voltage will burn out the analog input resistor in a hurry, the internal ones are typically 1/8W or less.

6. Use the 4-20mA control output of PID loop controller that has a manual mode which overrides automatic mode. Put the controller in manual mode and display the output value (probably in percent)and run the output up or down until the output is 10mA or 37.5%.

7. Remove the faulty instrument from the loop and replace it with an RTD transmitter
10mA = 6/16 = 37.5% of a 4-20mA span.
Use a common resistor, like 120 Ohms, as an input to the transmitter. 120 Ohms would be 51.6°C for Pt100. 51.6°C is 37.5% of 137.6°C. Configure the transmitter for 0 to 137.6°C and the transmitter will output 10mA.
Excellent ideas—all!

But if you “ … can’t get access to the PLC … “ )and you didn’t say for how long you wouldn’t have access ….) then you have to improvise, and sometimes that means a little more “effort” than usual.

Blessed day.