Transmitter connection with both PLC and recorder

The differential pressure transmitter output(4 to 20 mA) is connected with PLC. Now i want to connect with recorder too in series with PLC. Transmitter output is 4 to 20 mA. Recorder input requirement is 1 to 5V. I am thinking to connect 250 ohm resistor in series and then connect the recorder across resistor.

Could anybody tell me please my idea is good or make problem.
Your earliest reply will be great help.

Your assumption should get you what you want

When you apply Ohms law to your figures provided

0.020 x 250 = 5 volts
0.004 x 250 = 1 volt
across the series 250 ohm resistor

You might find that the PLC's input has a 250 ohm resistor across it and all you have to do is parallel the PLC's AI (+) and (-) connections to the recorder.

To check it, put a voltmeter across the input and see whether the voltage corresponds to a 1.0 to 5.0 span that a 250 ohm resistor would have for a 4-20mA span, i.e. 12.0mA = 3.00V

A couple of cautions.

First, make sure the transmitter can handle the total load in the circuit. You will have 250 Ohm at the recorder, probably 250 Ohms at the PLC, and some resistance in the loop wiring. Your transmitter is probably rated for a maximum load of around 600 Ohms, so you are probably OK, but you need to check this. If you have any other devices in the loop, like a local indicator or such, or if your transmitter supply voltage is low, or if your transmitter has a low load rating, you will be in trouble.

Second, most PLCs have one side of the 4-20 mA input tied to ground. Many chart recorders do the same thing. This creates what is called a ground loop - only the first device gets the current signal, which goes to ground instead of to the second device in the loop. If this is the case I suggest you put an isolated signal conditioner in the loop at the chart recorder and ahead of the PLC. The conditioner will be low impedence (verify) and can provide a 1-5 VDC for the recorder and let the current signal continue through the loop to the PLC.