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Endress Hauser Flow Meter Configuration Tutorial: Setting Up 4-20mA Outputs and Modbus
Quick Answer: You set the 4-20mA output on an Endress Hauser flow meter under Setup, Current Output, Assign. For Modbus RTU, set the slave address, baud rate, parity, and register format. Silver Automation Instruments supplies flow meters with 4-20mA HART and Modbus RTU if you need an alternative.
This Endress Hauser flow meter configuration tutorial covers the field settings that engineers and technicians use most often. We see the same issues on customer sites in Vietnam, Malaysia, Oman, and Chile. A small setting error in the current output or Modbus register map can cause a 10 percent reading error or a complete loss of signal.
4-20mA Output Setup on Endress Hauser Flow Meters
Most Endress Hauser transmitters have a local display with push buttons. Go to Setup, then Current Output. The first parameter is Assign. This maps the 4-20mA loop to a process variable. You can choose volume flow, mass flow, corrected volume flow, temperature, or density. A Coriolis meter can also output density in kg/m3, temperature in °C, or viscosity in cP if the transmitter has the right software.
Then set the 4 mA value and the 20 mA value. For example, a DN15 Coriolis meter on additive dosing may run from 0 kg/h to 50 kg/h. Set 4 mA at 0 kg/h and 20 mA at 50 kg/h. A DN25 Coriolis meter on a palm oil line in Malaysia may run from 0 kg/h to 6000 kg/h. Set 4 mA at 0 kg/h and 20 mA at 6000 kg/h. Do not set the range too wide. If the normal flow is only 400 kg/h on a 0 to 10000 kg/h scale, the PLC resolution gets rough. Most engineers set the upper range 10 to 20 percent above the normal operating point. A paint manufacturer in Indonesia once set the 20 mA value below the normal batch flow. The DCS read a saturated signal and the batch controller lost its target.
Check the alarm action. The output can fall to 3.6 mA or rise to 22 mA when the meter detects an empty pipe or a sensor fault. Many water plants in the Middle East use 22 mA as a high alarm. This helps the DCS identify a fault quickly. Some systems expect 3.6 mA as a low alarm. Most engineers skip this part. Then an empty pipe during a water hammer event sends the DCS a false reading.
Modbus RTU Settings for Endress Hauser Flow Meters
Modbus on Endress Hauser flow meters is normally RS485 with Modbus RTU. The meter is a slave device. You need a USB to RS485 converter or a PLC with a Modbus master. Set the device address between 1 and 247. Do not use address 0. Because address 0 is a broadcast address, no slave responds.
Baud rate and parity must match the master. Common settings in water treatment plants are 19200 baud, even parity, 8 data bits, and 1 stop bit. Oil and gas sites often use 9600 baud and no parity. In practice, if the settings do not match, the master gets no response or a CRC error.
Register mapping is the part that causes most confusion. Endress Hauser uses integer and floating point registers. A 32 bit float may be split across two registers. You may need to swap the word order or byte order. We saw this on a wastewater site in Vietnam where the DCS read 0.12 m3/h on a DN100 electromagnetic flow meter that was actually 120 m3/h. The two Modbus registers were swapped.
Wiring and Field Checks
For 4-20mA output, use twisted pair shielded cable. Keep the cable away
For Modbus RS485, wire A to A and B to B. Some vendors reverse the A and B labels. So if the meter does not respond, swap the two data lines and test again. Use 120 ohm termination resistors at both ends of the bus. Long cable runs above 300 meters often need bias resistors.
For ATEX Zone 1 areas, use an approved meter and check the output isolation. A certified Ex barrier may be needed between the meter and the PLC. For gas or heat metering, some transmitters accept a PT100 input for temperature compensation.
When to Replace an Endress Hauser Meter with a Silver Instruments Model
Endress Hauser flow meters are reliable but spare parts and configuration support can be slow in some regions. Silver Automation Instruments supplies Coriolis, electromagnetic, ultrasonic, vortex, oval gear, and thermal mass flow meters. Many models support 4-20mA HART and Modbus RTU. We ship to Southeast Asia, Oceania, Latin America, Africa, and the Middle East.
Here is the thing. A customer in the Philippines needed a DN50 electromagnetic flow meter for seawater service at a desalination plant. The original Endress Hauser unit had a 6 week lead time. Silver Instruments supplied a compatible DN50 electromagnetic flow meter with 4-20mA output, RS485 Modbus, and PTFE liner in 8 days. The total cost was lower and the output mapping was already set to their flow range.
Our team can help you set the 4-20mA output and Modbus parameters before shipping. Send us your pressure (bar), temperature (°C), pipe size (DN), and flow range. We will recommend a model and give you a price.
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FAQ
How do I set a 4-20mA output on an Endress Hauser flow meter?
Go to Setup, Current Output, Assign. Choose the process variable. Then set the 4 mA and 20 mA values to your process range. Check the alarm action and the damping value.
What are the common Modbus RTU settings for Endress Hauser flow meters?
Most sites use 19200 baud, even parity, 8 data bits, and 1 stop bit. The slave address can be 1 to 247. Match the register data type and byte order with the DCS or PLC.
Can I use Modbus and 4-20mA at the same time?
Yes. Many Endress Hauser transmitters support simultaneous outputs. You can send a strong 4-20mA signal to the local DCS and use Modbus for totalizers or diagnostic data.
Why does my Modbus flow reading show a very small or wrong value?
Check the register word order and byte order. A swapped high and low word can turn 120 m3/h into 0.12 m3/h. Also check the scale factor and data type. Some registers are signed integers, not floats.
What flow meters can Silver Automation Instruments supply as alternatives?
We supply Coriolis mass flow meters, electromagnetic flow meters, ultrasonic flow meters, vortex flow meters, oval gear flow meters for diesel, thermal mass flow meters, pressure transmitters, and paperless recorders. These handle flow in m3/h, pressure in bar, temperature in °C, and conductivity in µS/cm. Send us your process data and we will recommend a model.
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