Knowledge Base

Communication options for Alicat instruments

Every Alicat device is equipped with at least one of the following communication protocols:

Analog (4-20 mA, 0-10 Vdc, 0-5 Vdc, or 1-5 Vdc)
ASCII over RS-232 or RS-485
DeviceNET
EtherCAT
EtherNet/IP
IO-Link
Modbus RTU
Modbus TCP/IP
PROFIBUS
PROFINET

In this article, we present an overview of these communication protocols including electrical requirements, device and software compatibility, and network topologies

ASCII and Modbus RTU over RS-232

Alicat devices come default with ASCII and Modbus RTU over RS-232. RS-232 interfaces are useful in systems with short-range, low-speed wired data connection. This is an inexpensive option when you only need to communicate with 26 to 32 devices in low-noise environments.

How Alicat’s RS-232 communication works

Modbus RTU has a simple setup and low memory requirement compared to most industrial protocols. It also has broad support among industrial control hardware and software systems. Modbus RTU has a standard set of universal commands, making it easy to use for those who are already familiar with the protocol.

ASCII or Modbus over RS-232 specifications

Alicat part number: [default]; -MODBUS on older devices
Analog signals: Yes
Optional certifications: IP66/67; CSA Class 1/Div 2
Electrical connections: Default 8 pin mini-DIN (other options available)
Power over protocol connector: Available
Dedicated power jack: Yes
Additional power requirement: None
Device compatibility: All devices**
- Available with display?: Yes
- Available via retrofitting to standard device?: Yes
Software compatibility: Serial terminals (Alicat Terminal, HyperTerminal, PuTTy); FlowVision 2.0; LabVIEW; Modbus poll (Modbus only)
Max number of devices on network: 26 (ASCII) or 32* (Modbus)
- Topologies: Linear; star

*BASIS devices can have 247 Modbus devices on a network.

**CODA not compatible with Alicat’s ASCII.

Software and drivers

Resources

Serial communications primer
Modbus operating bulletin
Modbus Poll Data Registers – MBP file – This loads the configuration requirements required to read the available data registers on any Modbus-equipped Alicat device and is useful for troubleshooting and viewing the required Modbus data settings.

Limitations

Lower transmission speed compared with RS-485 and Ethernet.
Operational across short distances only. Speed falls off considerably with distance.
Not usable in high noise environments.

Serial communication tutorial

ASCII and Modbus RTU over RS-485

Choose ASCII and Modbus RTU over RS-485 if you are transmitting data across long distances or in a high noise environment. RS-485 can communicate with 26 to 32 devices at once, so larger systems will require an additional industrial protocol (see below).

ASCII over RS-485 is compatible with most devices, excluding CODA and portable options.

ASCII or Modbus RTU over RS-485 specifications

Alicat part number: -485; -MODBUS-485 on older devices
Analog signals: Yes
Optional certifications: IP66/67; CSA Class 1/Div 2
Electrical connections: Default 8 pin mini-DIN (other options available)
Power over protocol connector: Available
Dedicated power jack: Yes
Additional power requirement: None
Device compatibility: All devices except portables**
- Available with display?: Yes
- Available via retrofitting to standard device?: Yes
Software compatibility: Serial terminals (Alicat Terminal, HyperTerminal, PuTTy); FlowVision 2.0; LabVIEW; Modbus poll (Modbus only)
Max number of devices on network: 26 (ASCII) or 32* (Modbus)
- Topologies: Linear with termination resistor (120 Ohm)

*BASIS devices can have 247 Modbus devices on a network.

**CODA not compatible with Alicat’s ASCII.

Resources

Serial communications primer
Modbus operating bulletin
Modbus Poll Data Registers – MBP file – This loads the configuration requirements required to read the available data registers on any Modbus-equipped Alicat device and is useful for troubleshooting and viewing the required Modbus data settings.

Limitations

Connecting to a computer will typically require the purchase of an RS-485 card.

Modbus FAQ

DeviceNET

DeviceNET is a common choice for automation or factory-type settings and can be used to communicate with up to 64 devices. This option has the most limited options for device configurations and is only available with standard devices with no display.

DeviceNET specifications

Alicat part number: -DNET
Secondary protocol: ASCII over RS-232 (primarily for debugging)
Electrical connections: Male 5-pin M12 connector for DeviceNET (top port) and male 9-pin D-sub connector for RS-232 comms (side port)
Power over protocol connector: Required
Dedicated power jack: No
Additional power requirement: 170 mA
Device compatibility: Incompatible with CODA, BASIS, EPC, Class 1 Division 2, and portable devices
- Available with display?: No
- Available via retrofitting to standard device?: No
Max number of devices on network: 64
- Topologies: Trunk with drop lines

Resources

Limitations

Requires a PLC.
Incompatible with CODA, BASIS, EPC, Class 1 Division 2, and portable devices.
No display.
No analog signals.
More expensive than ASCII or Modbus.
Requires 170 mA power.

DeviceNET FAQ

EtherCAT

EtherCAT is the fastest industrial Ethernet technology, with data transmission rates up to 100 mbps.

EtherCAT specifications

Alicat part number: -ECAT
Electrical connections: Comms over dual RJ45
Power over protocol connector: No
Dedicated power jack: Required
Additional power requirement: 120 mA
Device compatibility: Incompatible with BASIS, EPC, Class 1 Division 2, and portable devices
- Available with display?: Yes
- Available via retrofitting to standard device?: No
Network topologies: Star; linear

Resources

Limitations

Requires a PLC.
Incompatible with BASIS, EPC, Class 1 Division 2, and portable devices.
No analog signals.
More expensive than ASCII or Modbus.
Requires 120 mA power.

EtherCAT FAQ

EtherNet/IP

EtherNet/IP is one of the most popular industrial protocols, and can be thought of as a newer version of DeviceNET that is able to communicate with an unlimited number of devices. Like DeviceNET, it is only available with standard devices but has the added option of a display.

EtherNet/IP specifications

Alicat part number: -EIP
Electrical connections: Comms over dual RJ45
Power over protocol connector: No
Dedicated power jack: Required
Additional power requirement: 120 mA
Device compatibility: Incompatible with BASIS, EPC, Class 1 Division 2, and portable devices
- Available with display?: Yes
- Available via retrofitting to standard device?: No
Max number of devices on network: No limit
- Topologies: Star; linear; ring

Resources

Limitations

Requires a PLC.
Incompatible with BASIS, EPC, Class 1 Division 2, and portable devices.
No analog signals.
More expensive than ASCII or Modbus.
Requires 120 mA power.

EtherNet/IP FAQ

IO-Link

IO-Link is a bi-directional, digital, point-to-point industrial networking protocol. It allows users to directly interface with multiple devices via higher-level controller. Because of its compatibility with common industrial architectures, such as Fieldbus and industrial Ethernet, it can be easily connected to existing PLCs or HMIs using standard connectors.

IO-Link specifications

Alicat part number: -IOLINKA (Class A) or -IOLINKB (Class B)
Electrical connections: M12
Power over protocol connector: Yes
Dedicated power jack: No
Device compatibility:Incompatible with Basis, CODA, Class 1 Div 1, Class 1 Div 2, and portable devices
- Available with display?: Yes
- Available via retrofitting to standard device?: No
Max number of devices on network: Determined by the IO-Link master

Resources

Manual
IODD files and Manufacturer’s Declarations (links to IO-Link.com)

Limitations

Requires an IO-Link master to be used
Incompatible with Basis, CODA, Class 1 Div 1, Class 1 Div 2, and portable devices

IO-LInk FAQ

Modbus TCP/IP

Modbus TCP/IP is the simplest of ethernet protocols and was created for integration with pre-existing TCP/IP set ups. Use Modbus TCP/IP to communicate with an unlimited number of devices. Like EtherNet/IP, it is only available with standard devices with the option for a display.

Modbus TCP/IP specifications

Alicat part number: -MODTCPIP
Electrical connections: Comms over dual RJ45
Power over protocol connector: No
Dedicated power jack: Required
Additional power requirement: 120 mA
Device compatibility: Incompatible with CODA, BASIS, EPC, Class 1 Division 2, and portable devices
- Available with display?: Yes
- Available via retrofitting to standard device?: No
Software compatibility: LabVIEW; Modbus Poll
Max number of devices on network: No limit
- Topologies: Star; linear

Resources

Modbus operating bulletin
Modbus Poll Data Registers – MBP file – This loads the configuration requirements required to read the available data registers on any Modbus-equipped Alicat device and is useful for troubleshooting and viewing the required Modbus data settings.

Limitations

Incompatible with CODA, BASIS, EPC, Class 1 Division 2, and portable devices.
No analog signals.
More expensive than ASCII or Modbus.
Requires 120 mA power.

Modbus TCP/IP FAQ

PROFIBUS DP-V0

Many Alicat devices are available with PROFIBUS for communication with up to 125 devices. PROFIBUS is an open specification communication standard designed for automation equipment.

PROFIBUS specifications

Alicat part number: -PROFIBUS
Secondary protocol: ASCII over RS-232 (primarily for debugging)
Optional certifications: IP66/67
Electrical connections: 9-pin D-sub PROFIBUS connector next to a 4-pin M8 connector for RS-232 communication and power
Power over protocol connector: Available
Dedicated power jack: No
Additional power requirement: 120 mA
Device compatibility: Incompatible with CODA, BASIS, EPC, Class 1 Division 2, and portable devices
- Available with display?: Yes
- Available via retrofitting to standard device?: No
Software compatibility: Serial terminals (Alicat Terminal, HyperTerminal, PuTTy); FlowVision 2.0
Max number of devices on network: 125
- Topologies: Linear with termination resistor

Resources

For instruments built after* July 12, 2020:

For instruments built before July 12, 2020:

*Customers with the GSD file for instruments built prior to July 12, 2020 file may continue using it with new units if your system is already configured.

Limitations

To communicate with the Alicat, users must have a PROFIBUS card inside of a PC or a PROFIBUS-enabled PLC.
Incompatible with CODA, BASIS, EPC, Class 1 Division 2, and portable devices.
Not as fast as analog or ASCII serial communication.
More expensive than ASCII or Modbus.
Requires 120 mA power.

PROFIBUS-FAQ

PROFINET

PROFINET is an industry technical standard for data communication over Industrial Ethernet, designed for collecting data from, and controlling equipment in industrial systems, with a particular strength in delivering data under tight time constraints.

PROFINET specifications

Alicat part number: -PROFINET
Electrical connections: Dual RJ45
Power over protocol connector: No
Dedicated power jack: Required
Additional power requirement: 75 mA
Device compatibility: Incompatible with BASIS, EPC, Class 1 Division 2, and portable devices
- Available with display?: Yes
- Available via retrofitting to standard device?: No
Max number of devices on network: No limit
- Topologies: Star; tree; line; ring

Resources

Limitations

Requires a PLC.
Incompatible with BASIS, EPC, Class 1 Division 2, and portable devices.
No analog I/O.
More expensive than ASCII or Modbus RTU.
Requires 75 mA power.

PROFINET-FAQ

FastTrack Ordering

M/MC mass flow meters and controllers that ship in just 3-5 business days.

CALIBRATION

Standard or High Accuracy

DISPLAY

Monochrome, Color, or None

PROTOCOL

Analog, RS-232, RS-485, or Modbus RTU

CONNECTOR

MD8, Locking Industrial, DB9M, DB15

FITTINGS

NPT

METER RANGES

2 SCCM - 500SLPM

CONTROLLER RANGES

2 SCCM - 100SLPM

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