In order for secondary communication and data gathering, digital water flow meters usually are equipped with various of outputs and protocol.Only learn them better, users can use them rightly and properly.
1.Analog Current Outputs: 4-20mA or 0-20mA
Current output is simple and easy to use. It is one of the most popular output in industry control. But it is easy interrupted.Its typical way is 4-20mA.
In flow,it is usually to output instant flow rate. It can be programmed(e.g.our ultrasonic flow meter) or not programmed(e.g.flow sensor).
4-20mA in flow is usually 2-wire system and have self-power or loop-power way.
2.Analog Voltage Outputs:0-5VDC or 0-10VDC
Voltage output is similar to current output. But it utilizes voltage to output signal. It is simple and easy to operate. It is used to output instant flow rate in flow measurement. Comparing with current output, it is less used for flow meters.
3.Pulse Output: OCT or Hall Effect
Pulse output is one main output for flow meter. It is used to output flow totalizer and use pulse quantity to express flow rate. OCT pulse is industrial class and have a better performance. Hall effect is often used for flow sensors.
Frequency output is not main output and it is a kind of compensation for pulse.Of course, if you have such requirement, please feel free to contact us. Our ultrasonic flow meters have been equipped with such output.
5.Switch Output: NPN/PNP, Relay,etc.
Switch output is used to open/close flow by controlling pump or valve.Here user should pay much more attention for controlling details. For example, flow meters may be equipped with weak current and it can’t be used for direct control.It requires intermediate relay.
But for flow switch,its current may be big enough to control.
User should notice it,otherwise your flow device may be damaged.
Except relay output,NPN/PNP is often used for flow switches.
6.Digital RS485/RS232 output
RS485/RS232 belong to serial port. They are digital output and direct reading way,so have a higher accuracy than analog output. Meanwhile, it can output more data. This is much useful for digital flow meters.Because digital flow meters have more functions than mechanical flow meters.
RS232 are more suitable for data downloading from portable flow meters, or used for communication with computer. If want secondary industrial gathering, RS485 is more used because had a longer communication distance than RS232.
7.TTL Electric Level
TTL is a kind of electric level. It is digital output.Comparing RS485/RS232,its power consumption is less. It is often used for system debugging or low power consumption of electronic water meters.
Modbus is a popular industrial communication protocol.It is suitable for making network to manage many of flow devices by controller center.
Modbus-RTU and Modbus-ASII are two main ways for industry application. Comparing with Modbus-ASII,Modbus-RTU is recommended because it is simpler.
Should notice there is a kind of transferring Modbus in the market. This way can only provide several addresses by borrowing a converter module. This is not recommended.
Modbus is just protocol software and it also requires hardware wire. Usually,it borrows RS485 as its hardware channel.
If you want to learn more details about Modbus flow meter, please feel free to contact us.
HART is often used for pressure transmitter, temperature transmitter, Radar level transmitter,etc. It usually uses 4-20mA as its output wire. As 4-20mA is widely existed, it has bigger application range.
HART is not suitable for network. Thus,its prospect is not so good like Modbus. Hart is not often used in flow.
Complete version HART output can provide bi-direction. Users can gather data and set parameters by it. But recently, several companies provide transferring type which can only gather part of datas,but can’t be used for parameters setup. This is not useful and you have to pay much more for it.
Radio RF is used to gather data in flow measurement. It has shorter communication distance and lower power consumption. It is often used with handheld terminals.
USB has been must for computer. But it is mainly equipped with portable flow meters. It is used for big data downloading. Thus, if you flow meter has data logger with a bigger memory, you may require one.
But for most of application,it is not necessary.
After all,a USB reader or USB/RS232 converter is a cheaper solution.
Infrared and Bluetooth are mainly used to parameters setup and communication.Both of them are less than for online data gathering. Thus, they are not often seen.
Infrared is more often used than Bluetooth because its IC solution is simpler and cheaper.
WIFI has been a main wireless way in our homes,but it has a bigger power consumption and shorter communication distance. Thus,it is not very suitable for water flow meters because water flow meters are usually installed far from homes.It has a farther distance and not easy to provide power.
Zigbee may be a better choice for wireless communication of flow meters. It has been released for several years and proving its value. It has been widely used for internet of things.
LoRa is a new released wireless technology with low power consumption and aim to solve the hard problem of low power wireless communication. It has been used with water meters. Its prospect requires to wait.
GSM/GPRS has been proved technology since 2G period.
It uses communication way managed by mobile management company and pay as flow data.
Flow devices output their data by analog,pulse and digital port. Then GSM/GPRS unit will transmit related data to server.
Different flow meter manufacturer may have their own consideration for which outs added to their product. Thus, when you make a selection,it is better to contact re-sellers before placing final order if you are not sure.
Limited by length, we can list all detailed information about these outputs and protocols. Of course,you don’t need to master all of them. If you have any questions,please feel free to contact us and our experienced engineer will assist you.