Distinguishing among communication options

This article presents an overview of Alicat’s various communication options. For more detailed specifications, check this page

Choosing the best communication protocol to work with your Alicat devices depends on factors such as: 

  • Preference for analog, serial, or industrial protocol communication 
  • Required operating distance 
  • Required data transfer speed 
  • Desired device linking configurations 
  • Total number of connected devices 
  • Familiarity with communication options  
  • Desired data accuracy  

Alicat provides various analog, serial, and industrial protocol communication options to meet all of your specific application needs.  

What is the difference between analog, serial, and industrial protocol communication options?
Analog communications transfer device information using either continuous current or voltage data whereas serial and industrial protocol communication options rely on digital signals that consist of discrete data in binary form. Whereas analog signals require end user interpretation of raw electrical signals, serial communications work with communication layers such as industrial protocols or software programs such as FlowVision 2.0 to interpret their binary signals. Industrial protocols are the standardized control systems that handle various manufacturing automation processes. Many Alicat devices can switch between analog and serial control.

Alicat analog communication options  

Alicat offers analog communication options which transfer data via either current or voltage. Due to voltage drop, current is preferable for long operating lengths. Conversely, voltage provides more control options. Compared to serial communications, analog signals may have up to 0.25% additional reading error. Alicat’s analog options include: 

  • 0-5 Volts 
  • 0-10 Volts 
  • 1-5 Volts  
  • 4-20 mA 

Alicat serial protocols  

The Alicat serial command interface is the native communications interface used for control, calibration, and programming of all Alicat devices. This interface uses ASCII over either RS-232 or RS-485, with RS-232 being the default option. This is the most powerful way to communicate with and program an Alicat device as all the in house software such as FlowVision 2.0 is built around this framework.  

What is the difference RS-232 and RS-485?
RS-485 and RS-232 are the two physical layer options which describe the electrical behavior used to communicate serial commands on Alicat devices. Both RS-485 and RS-232 use three communication wires for sending and receiving data. Whereas RS-232 uses one ground wire, one for receiving, and one for transmitting data, RS-485 uses one wire for ground while the other two wires can both transmit and receive data. RS-485 is best for communicating over long lengths of cable, in environments with lots of radiofrequency noise and is faster whereas RS-232 is better suited for star topology device linking setups.

Every Alicat device uses a base circuit board that is either in RS-232 or RS-485 which then communicates with a compatible industrial protocol or other control system either physically or via software.  

Alicat offers FlowVision 2.0 and Alicat Serial Terminal options for communicating serial commands with devices. Alicat’s Serial Terminal offers command line communication whereas FlowVision 2.0 is proprietary Alicat software with many different control options embedded into the program. Additionally, programs like LabViewPutty, and Python can also communicate with Alicat devices serially. Technically, some industrial protocols also communicate with serial commands however they will be covered in the next section.  

Alicat industrial protocol options 

The manufacturing controls are organized in common ways, independent of the protocols used. Some of these options involve use of process level controllers or PLCs which do small computing and control tasks. Alternatively, human-machine interfaces or HMIs display information and provide limited, programmable control over PLCs. Additionally, supervisory control & data acquisition or SCADA systems integrate data from large networks of sub-processes to make it easier to command and control entire factories. 

Industrial computers which use industrial protocol communication options are designed to be programmed by technicians already familiar with the mechanical automation and electrical relays. Because of this, they are programmed using simple, often graphical programming languages. 

Analog control is not compatible with devices using most industrial protocols (exception is Modbus RTU). All industrial protocols can run via compatible PLCs or using specialized hardware on PCs. Modbus RTU and Modbus TCP/IP require the least amount of specialized hardware to work on PCs. With exception to Modbus RTU, IP devices are not available with Basis, EPC, CSA Class 1 Div 1 or Class 1 Div 2 certified, or portable configurations.  

Alicat currently offers 6 different industrial protocol communication options, including: 

Modbus RTU  

  • Modbus over RS-232 or Modbus over RS-485 communication options. 
  • Openly published and royalty free.  
  • Uses a master/slave architecture. 
  • Does not require any special hardware configuration (works well with PCs). 

Modbus TCP/IP  

  • Modbus software layer over Ethernet. 
  • Works with both PCs and PLCs like Modbus RTU. 
  • When using a PC, requires Modbus Poll or another Modbus program to operate. 
  • Able to use remote connections. 
  • Uses a master/slave architecture with no limit on total number of devices. 


  • Device must be assigned an IP address to connect to the network. 
  • There is no practical method to use EtherNet/IP with a PC. It must use a PLC. 


  • Designed with short data update times allowing sub 1ms cycle times. 
  • Can be connected in linear or star topologies. 
  • Works with any EtherCAT capable PLC  


  • Communicates over CAN (Controller Area Network) technology. 
  • Supports both master/slave and peer-to-peer architecture. 
  • Power is provided over the network bus. 


  • Data is transferred over RS-485 serial communication.
  • Requires master/slave architecture (either PROFIBUS card inside of a PC, or a PROFIBUS enabled PLC). 
  • Option to power over PROFIBUS.

Additional support 

FastTrack Ordering

M/MC mass flow meters and controllers that ship in just 3-5 business days.
Standard or High Accuracy
Monochrome, Color, or None
Analog, RS-232, RS-485, or Modbus RTU
MD8, Locking Industrial, DB9M, DB15


2 SCCM - 500SLPM


2 SCCM - 100SLPM

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