SCADALink IP100 for Modbus TCP and Modbus RTU I/O Expansion

Often in new or legacy automation applications there is a requirement to add local or remote I/O.

Modbus TCP, and Modbus RTU protocol is a common protocol supported by almost all SCADA Software, DCS, PLC, RTU, and Flow Computer manufacturers.

Supporting Modbus TCP and Modbus RTU Protocols; and having I/O bus,  the SCADALink IP100 can be a used for I/O expansion in new or legacy systems.

The SCADALink IP100 supports connectivity to up to 10 SCADALink Modular I/O modules of any type including:

  • DI8  – 8 Dry Contact Inputs
  • DO8 –   8 Relays Output
  • AI4  – AI4 – 4 x Isolated 4-20ma Output
  • AO4 – 4 x Isolated 4-20ma Output
  • COMBO-I/O – 2 DI/2DO,1 AI, 1 AO .

SCADALink I/O Expansion Modules integrated with the IP100 are mapped as a single Modbus device (Modbus TCP or RTU).

SCADALink I/O Expansion Modules featuring isolated I/O, low power 10-30 VDC operation, Class I Div 2 certification, and standard Modbus protocol support is an ideal I/O expansion solution for remote RTU applications where the RTU or Flow Computer is out of I/O.

In addition, the SCADALink IP100 can also be used as a Modbus Ethernet-Serial Gateway for RS485 and RS232 instrumentation/devices at remote sites.

SCADALink IP100 with COMBO I/O  (1 AI,1AO, 2 DI, 2 DO) Module











SCADALink IP100 with DI8 and AI4 Module


Industrial Solar Power System Troubleshooting

Solar Power Systems are used in remote industrial applications where there is no line power. Properly designed, installed, and maintained industrial solar power systems will have  high uptime and low maintenance.

SCADALink has successful supplied 1000’s of green and brown field solar power systems for remote instrumentation and control systems. Often our clients have commented about challenges they have had with their existing solar power systems.

In this blog we will discuss solar system problems; steps to diagnose problems; and solutions.

Potential Problems

Possible Problems include:

  • Indequate Solar Charging Capacity
  • Inadequte Battery Bank Sizing
  • Battery Overcharging
  • Extreme Battery Temperatures
  • Solar Panel Shading
  • Improper Installation
  • Oversized Solar Power Systems

Solar Power System Troubleshooting and Analysis

  • Get Accurate Load Profile – Accurately estimate or measure system loads.  Measure functioning equipment if possible.
  • Properly Sizing Solar Array –  Charge 1.25 to 1.5 x average load at lowest season of solar isolation.
  • Properly Size Battery Banks – Size to 10 to 15 days for autonomy at -40 degrees C. More required days for critical application and northerly environment with lower temperature, and lower sun.
  • Site Visit to assess existing installation.
  • On larger battery banks – Minimize number of parallel batteries strings.
  • Proper Installation
  • Make sure Solar Panels are oriented in optimum direction.


Solar Panel Mounting and Orientation

Mount Panels high enough to prevent shading from vehicles, nearby structures, or trees. Angle solar panels suitable for environment to maximum solar isolation. In northern climates, install solar panels in vertically (near 90 degrees elevation angle) to shed snow and prevent snow build up.  Typically solar panel arrray are pointed 180 degrees S of N in the azimuth (directly south) unless that direction is shaded.

Solar Power System Monitoring

Incorporate remote voltage and current monitoring to can give an indication of power system health and warm of impending problems.  Many RTU, PLC,  and modems have integrated supply voltage monitoring.  For sites without existing voltage monitoring capacity one can use the SCADALink RIO100.  New larger solar regulators mady have these integrated features.  For larger solar power systems, battery management systems should be deployed.

Monitoring trends of voltage and current over time can help indicate proper solar system operation.


Insulated Battery Enclosures

The use of insulated enclosures or buildings can help maintain temperature of battery bank to maintain its load capacity.  AGM batteries at -40 degrees C will have 50% of the AH capacity at 0 degrees C.

Solar Charge Regulator Selection

Use Solar Charge Regulators with Low Voltage Disconnect to prevent batttery damage.  Utilize MPPT Charger optimize charge batteries during lower sunlight conditions. Ensure voltage input specs for solar regulators match the solar panel array voltage output. Excess solar array output voltage can result in shut-down or regulator damage. Shutdowns will result in lower total charge from solar panel array. Inadequate voltage will result to lower charge from solar panel array.

Solar Hybrid System incorporating Generators and Fuel Cells

For remote sites with larger loads, it may be necessary to integrate additional  charging mechanisms such as generators, fuel cells, and wind turbines into a solar hybrid system to provide adequate charging capacity such as that deployed in SCADALINK SOLARIS 3000.



Starlink for SCADA & Remote Monitoring

With the rapid advent of the Starlink Satellite Network, Starlink is seeing increasing use for SCADA & Remote Monitoring applications where there are no reliable terrestrial communications such as DSL, fiber, or cellular.

With its high bandwidth and unlimited data at a relatively low cost,  Starlink is becoming an alternative satellite communications technology vs VSAT, BGAN, or Iridium satellite solutions.  A advantage of Starlink compared to VSAT solutions is the low deployment cost as the result of small size and autopointing technolgy. No specially trained satellite technicians are required to point the antenna system.  The unlimited data plans make Starlink deployments affordable compared to BGAN and Iridium satellite solutions.

Starlink being a Low Earth Orbit (LEO) satellite system will have better coverage in rugged terrain with southerly obstructions compared to Geosynchroneous (GEO) satellite systems in areas where Starlink coverage is deployed.

The SCADAlink SatConnect Gateway integrates Starlink and Cellular communications technology in a rapid deploy solution ideal for remote Industrial Applications such as Oil and Gas; and Mining.

Combining Cellular and Unlicensed 900 MHz Wireless for Critical Control Applications

In Pumping Applications, frequently there is need to transmit analog (4-20ma) or digital level sensor signals from a tank location to the pump locations for purposes of pump control.  900 Mhz wireless technology is most commonly used for these I/O Mirroring or I/O Telemetry applications.

In these applications,  distance between the pump and the tank can range from 100’s of yards to 5+ miles. In longer distance applications, terrain, foliage, or man-made structures can often prevent a reliable wireless communications path. Reliable communications is required to prevent tank overflow and/or pump shutdowns depending on how the pump control is implemented.

SCADALink RIO900 repeaters may be deployed or an alternative wireless communications technologies such as cellular can be used. The SCADALink RIO900 can be configured to utilize a redundant communication channels on one of its serial port interfaces.  The use of cellular communications on the RIO900 can help ensure reliable control operations as cellular may have better RF path due the height of the cellular towers.  For mobile or portable pumping applications, the dual communications feature can be invaluable.



Upgrade Cellular Devices Prior to 3G Cellular Network Sunset

The 3G Cellular Network Sunset in 2022 will affect operation of 3G based Cell phones, Modems, and Alarm Systems.

ATT 3G sunsetting is scheduled for Feb 22, 2022 with Verizon targeting the end of 2022.

For those in the Industrial Automation Industry this specifically applies to Cellular Modem/Routers, Alarm Auto-Dialers, and Connected Devices.  There may also be equipment in your operations that have embedded 3G cellular connectivity used for vendor equipment monitoring or maintenance.

Upgrade your Cellular Data Devices before the 3G Cellular Network Sunset affects your operation.





Remote Field Automation Device Connectivity

Automation Devices such as PLC, RTU, HMI, Smart Instrumentation, Power Meters and Flow Computers may have serial (RS232/RS485) and/or Ethernet Communications. In Automation Systems, these devices are commonly connected together via Industrial Protocols such as Modbus, Modbus TCP, Ethernet IP, and Profibus for SCADA, Data Acquisition, Operator Interface, and Control Purposes.

Additional Serial and Ethernet Connectivity to the individual devices may be required for monitoring, configuration,  support, maintenance, and troubleshooting.  Typically these device will will use the manufacturer’s proprietary software packages for configuration and maintenance.

For devices with Ethernet Connectivity the devices may be accessed using the same ethernet connectivity as the SCADA/Automation Protocol Communication. Sometimes, a separate Ethernet network is used to insure added security.

For devices with serial maintenance connectivity where maintenance must be performed on a separate serial port – a  LOI port, console port; or a USB port.  In these cases, a laptop with Manufacturer’s Software Packages is typically used for configuration and maintenance. When remote serial connectivity to the device is required,  Ethernet to Serial gateways can be used to provide remote connectivity to these devices.  Our SCADALink IP100 Industrial Terminal Server is commonly used for this application in addition to providing Modbus Ethernet to Modbus Serial Connectivity.

VPN’s network are used to provide secure access for maintenance connectivity when cellular or WAN connectivity is used to access to the automation/OT network.

The ability to have remote connectivity to automation device for maintenance can save time and money by reducing downtime and reducing travel. In remote field automation application, remote connectivity is a necessity due to the harsh work environment for field work.

Modbus I/O for 12 VDC Powered Systems


The SCADALink RIO100 Modbus I/O Controller and Analog I/O Expansion Modules can be used to provide stable high resolution I/O expansion for smaller RTU and Controller equipment and for control system operating on 12 VDC power systems.

I/O Expansion for Small RTU and Flow Computer Systems

Existing small RTU and EFM systems often do not have adequate integral I/O and sometimes require additional I/O expansion. The SCADAlink RIO100 Modbus I/O Controller can be used with I/O expansion modules to expand these RTU or EFM system I/O with up to 64 additional I/O points. Modular I/O Expansion include 4 Point 4-20ma Input (AI4), 4 Point Digital Input (DI8), 8 Point Digital Output (DO8), 4 Point 4-20ma Analog Output (AO4); and Combo I/O (1 AI, 1 AO, 2 DI, 2 DO).

A common application for Modbus I/O expansion to add casing and tubing pressure measurements to a EFM system on a gas production well.

The RIO100 system can be connected to RTU/EFM systems via RS232 or RS485 connections.

24 VDC Loop Power for 12VDC Powered Systems

The SCADALink AI4 and COMBO-I/O I/O Expansion Modules have integral 24VDC DC to DC Converters that generate 24 VDC Loop Power from a 10-30 VDC Supply Voltage. This allows provides stable 24VDC loop power for 4-20ma instrumentation operating on 12 VDC systems.  Frequently analog input channels do not operate reliably on 12 VDC power systems due to noisy power supply or inadequate 4-20ma loop voltage.

Isolated 4-20ma Inputs

SCADALink RIO100 Modbus I/O Expansion can be useful in applications where grounding issues can cause inaccurate or problematic analog input channels for PLC/RTU Controller with no-isolated analog inputs.



Wireless Pump Control for Small Water Systems

Remote Wireless Pump Control is a pervasive requirement in many industries.

A common Remote Pump Control application is to control pump operation based on a remote tank level. Pump(s) are started and stopped or the pump rate controlled to maintain a level in an elevated tank or reservoir. High and low level switches or level transmitters are used at the tanks to monitor the level for control and alarming.

Dedicated and Lease Line Replacement for Remote Pump Control

Where the tank and reservoir is close to the tank, level switches or level transmitter were hardwired to the pump control panel using dedicated cable. Over time, the dedicated cable may become damaged becoming difficult or costly to repair.

In other instances where the tank and reservoir are located a farther distance from the tank,  leased telephone lines were used.  Lease telco line can become damaged;  obsoleted by the telco or become overpriced.

In both these instances, wireless technology is viewed as replacement alternative. Technologies that can be used including Wireless I/O Telemetry, SCADA, and Wireless IoT.

Wireless I/O for Small Water Systems

It has been our experience that for Small Water Systems, Wireless I/O Telemetry is by far the most cost effective and easiest technology to deploy and maintain for Remote Pump Control in Small Water Systems. This is especially the case for Dedicate or Lease Line Replacement for existing Elevated Tank or Reservoirs since there is minimum number of signals required to be transmitted. It could range from 1 (Analog Tank Level) to 6 (Hi Level Switch, Low Level Switch, Hi-High Level, Intrusion, & Analog Tank Level) signals.

Wireless I/O Telemetry is the replacement of existing wired signals with Wireless Technology to mirror the I/O signals –  be it Digital Contacts or 4-20 ma Analog Signals.  With use of  Wirelesss I/O Replication Technology, no other part of an existing Control system needs to be changed.  The existing pump control panel can be retained. Hardware relay logic can be kept. This can be important for Small Water System applications where towns or villages may not have the personnel to deploy and maintain systems that require specialized programming or IT knowledge if PLC, HMI, or SCADA Systems are deployed.

Even in new Pump Control applications, Wireless I/O approach may be the most simple and most reliable solution for transmitting tank level signals.

SCADALink Wireless I/O Replacement Solutions are preconfigured and operational out of the box without configuration.  In the case where the remote tank location has no line power,  SCADALink Solar Powered Wireless I/O packages are available.





Remote Generator Monitoring and Control

Mobile Diesel Backup Generator for Office Building

Gas, Diesel, Natural Gas, and Propane Generators are seeing more pervasive use to provide emergency AC power during weather, fire, and flood emergencies.

Emergency Backup AC Power

Emergency Backup AC power is needed to provide backup power for critical AC loads at homes, offices, businesses, plants or telecommunication sites when grid AC power is lost due to weather emergencies.

Mobile AC Power

Mobile and Portable Generators may be deployed to power temporay equipment such as Pumps, and Lights.

Remote Monitoring and Control

For both Backup and Portable Generator applications, there is need for Remote Monitoring and Control.

Remote Monitoring is required to insure that backup power system is ready and available in case of emergency. Alarm Notification is required to alert personnel when an Generator is energized or has failed or is low on fuel.

Generator can be remotely control at remote unattended sites.

Remote could be as short distances as 100′ from a generator skid to the nearest electrical room for a plant or business. In these situations a Wireless I/O remote control solution could be utilized to monitor and control the generator versus running addition control wiring.

Alternately the Remote Monitoring and Control could be halfway across the continent and state for large Enterprise operations such a Telecom Company or Pipeline Company. In these situations, SatSCADA can be deployed.


PSC-24 Provides Stable 24VDC Control Power for Mobile Equipment

PSC 24 12 to 24vdc dinThe SCADALink PSC-24 DC to DC Converter is frequently used as a power conditioner to power PLC and Controllers used Mobile Equipment such as Pumps & Generators.

Mobile Equipment typically utilize 12/24 VDC Battery Systems charged by an alternator. PLC and Controller Equipment typically run directly off the 12/24VDC power system.

PLC and Controllers systems can be affected by voltage droops caused by cranking or by noisy DC power from alternator systems.

Voltage droops can cause PLC/controllers to restart or halt causing Pump or Generator shutdowns. Voltage droops can cause low supply voltage on 4-20ma Loops causing improper I/O readings causing improper control operation including shutdowns, unstable control, and incorrect process setpoints.

Noisy DC Power can often cause unstable, erratic, and noisy Analog Input Channels.

In addition, many PLC, Controllers, and Instruments are designed to run on 24 VDC Power and cannot operate or operate unreliably on 12 VDC power sources.  The PSC-24 can be used to provide stable 24VDC power from existing 12 to 24 VDC Battery Systems on Mobile Equipment.