A device to measure 4-20mA and re-transmit w/o loading
A device to measure 4-20mA and re-transmit w/o loading
(OP)
I'm trying to measure 4-20mA output signals from a pyrometer and manometer to a controller and measure the 4-20mA output signal of the controller so as to graph them via interface to a PC.By the time I get the signals through the interface to the PC I've lost much of the signals and can't graph properly.Is there a device to measure or compare the signal and re-transmit exactly?





RE: A device to measure 4-20mA and re-transmit w/o loading
<nbucska@pcperipherals.com>
RE: A device to measure 4-20mA and re-transmit w/o loading
RE: A device to measure 4-20mA and re-transmit w/o loading
As stated above you must load a current source to develop a signal. With out a load even a very small current will charge up a high impedance input line to it's compliance voltage, that is the max voltage that can be sourced. what most people do is to normalize the current for the desired signal level. ex: if your looking for a 4 to 20v signal then you must place a 1k resistor across the current to be measured, a 500 ohm res will give you 2 to 10 volts and so on. most pcb input interfaces have a very high input impedance so you don't normally need to worry about that.
elf
RE: A device to measure 4-20mA and re-transmit w/o loading
additionally most pc input cards are voltage input and single ended,and cannot be connected to a current output without a current sensing resistor, what type of card do you have?
RE: A device to measure 4-20mA and re-transmit w/o loading