Issue with the Yokogawa EJA530A pressure transmitter not being able to connect to the 475 handheld controller
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Dear colleagues: On site, we encountered an issue where the HART-compatible Yokogawa EJA530A pressure transmitter could not be connected to the Emerson 475 handheld controller. I would like to ask for your advice – during on-site debugging, I inserted a 250-ohm resistor, but still couldn’t establish a connection with the handheld controller. Eventually, I disconnected the system power supply and powered the device directly using a FLUKE744, and then communication became possible. What’s going on here? I’m again seeking your advice
Because the power supply is terrible. Interference is severe. Some small projects consider only the current signal and do not take the carrier voltage into account. So in this case, a clean power source must be used for calibration; battery power is the cleanest option. Switching power supplies that are half-wave rectified generally cannot be connected to a manual operator.
Is it powered by electricity from a secondary power supply?
The voltage is sufficient; it’s powered by a battery pack and solar energy, with a voltage of 26VDC
The power supply is based on solar energy plus a battery pack, with a voltage of 26VDC. In this case, what methods can be used to connect a manual controller?
There can’t be no 250 ohm resistor in the circuit, right?
The installation distance of the field transmitter is too far.
HART requires the loop impedance to be between 250 ohms and 600 ohms, with the resistor to be connected in the main loop.
It’s possible that it’s not the HART protocol
Yokogawa transmitters come with a dedicated handheld device called the BT200. This smart terminal can be used with all Yokogawa instruments that use BRAIN communication; you can first check whether your transmitter supports the HART communication protocol.