Step-by-Step Guide

Understanding Conventional Wire vs. Two-Wire

Conventional wire consists of a bundle of individual wires, typically number 14 gauge wire, with one common wire that serves as the loop back and multiple station wires. For example, a bundle of 20 zones would contain 21 wires total—one common and 20 station wires. The wire size can vary and may be smaller or larger depending on the installation.

Two-wire cable has a distinctly different physical appearance. It features an outer jacket made of high-density polyethylene that provides superior durability compared to conventional wire. The key functional difference is that two-wire carries both power and data out to the zones and back, while conventional wire primarily carries only power.

🚨Important!
Do not attempt to use two wires from a conventional wire bundle as a substitute for true two-wire cable. Conventional wire bundles often use PVC jacketing, which is porous and allows water to penetrate the wire path. This causes corrosion—visible as black discoloration when you strip back the wire. While this corrosion may not significantly impact power transmission, it severely affects data transmission, which requires a round trip from the controller to the device and back. Data loss typically occurs on the return path, resulting in error messages.

Using Powered BiCoders for Conventional Wire

The powered BiCoder is the solution for interfacing conventional wire with BaseStation controllers. This board features a series of terminals that connect to conventional wire paths and allows you to operate conventional wire using two-wire technology.

Powered BiCoders are available in two configurations: 12-zone and 24-zone models. 

Each board includes:

• Multiple terminals for conventional wire connections
• A rain jumper terminal
• A two-wire terminal for extending two-wire paths
• A power cable that connects to a transformer

The board is called "powered" because it requires a dedicated power source. Unlike standard BiCoders that receive power through the two-wire path, the powered BiCoder needs direct power input via its power cable to energize the circuitry that operates the conventional zones.

One significant advantage of powered BiCoders is that they support traditional conventional wire run lengths based on wire gauge (14, 12, or 18 gauge) because the board powers the zones directly with 24 volts. Standard two-wire BiCoders are limited to approximately 100 feet from BiCoder to solenoid, but powered BiCoders can accommodate the longer distances typical of conventional wire installations.

Creating Hybrid Systems

A powered BiCoder can support both conventional wire and two-wire on the same board. For example, you can connect 24 zones of conventional wire to the board's terminals and then extend a two-wire path from the board's two-wire terminal to pick up additional zones—up to the controller's maximum capacity of 200 zones total. This flexibility allows you to retrofit existing conventional systems while adding new two-wire zones as needed.

Understanding the Two Sides of a Powered BiCoder

A powered BiCoder essentially functions as a multi-zone BiCoder with the BiCoder technology built into the board. Understanding the two sides of the board is critical:

The two-wire side is where the board connects to the two-wire path that runs back to the controller. This connection is typically very short—sometimes just an inch long inside the controller cabinet.

The solenoid side is where all the conventional wire terminals are located. Each terminal connects to a zone wire that runs out to a solenoid, with the common wire returning to the board.

This distinction is important for troubleshooting. Any diagnostic messages or errors you receive from a powered BiCoder relate only to the solenoid side—the conventional wire runs and the solenoids themselves. Because the two-wire path is so short (often contained entirely within the controller cabinet), two-wire communication issues are extremely rare, though not impossible.

Connecting Soil Moisture Sensors to Conventional Wire

One of the most valuable features of powered BiCoders is the ability to add soil moisture sensors to conventional wire systems without running new wire. The powered BiCoder can transmit sensor data over the existing conventional wire path, making it one of the few exceptions where conventional wire carries data in addition to power.

Each powered BiCoder has specific terminals designated for soil moisture sensors:

• A1 and A2 terminals on the first bank
• B1 and B2 terminals on the second bank (on 24-zone models)

These are the only terminals on the board that will recognize and communicate with soil moisture sensors. If you connect a sensor to any other terminal (such as B8), the board will never detect it because it only has the capability to check the A1, A2, B1, and B2 terminals during search and assign operations.

🚨Important wiring requirement: To read a moisture sensor, the valve wire that the sensor is wired to in the field must land on post A1, A2, B1, or B2. This means each of these terminals will have both the solenoid connection and the moisture sensor connection.

On a 24-zone powered BiCoder, you can connect up to four soil moisture sensors total. While a BaseStation 3200 can handle up to 25 soil moisture sensors, you would need multiple powered BiCoder boards or use the two-wire path to accommodate that many sensors.

Note that only moisture sensors can be connected to the A1, A2, B1, and B2 terminals. Flow sensors and other two-wire devices cannot be connected to these specific posts—they must connect to the two-wire terminal on the board.

Installation Configurations

Powered BiCoders can be mounted in multiple orientations depending on the installation. In wall-mount controllers, they typically mount vertically on the side of the cabinet. In pedestal installations, they may be oriented horizontally or in other configurations depending on space constraints.

For factory installations, powered BiCoder boards come pre-mounted inside the controller cabinet. For example, a BaseStation 3200 can be ordered with two banks of 24-zone powered BiCoders already installed, providing 48 zones of conventional wire capacity right out of the box. The controller also includes the option to connect a two-wire path for additional zones.

Expanding Beyond Cabinet Capacity

While a controller may support a large number of zones (such as 200 zones on a BaseStation 3200), the physical cabinet may not have space to accommodate that much conventional wire. When the cabinet cannot physically fit all the required wire connections, you can install additional powered BiCoder boards in separate enclosures.

To connect multiple enclosures:

1. Install the BaseStation controller in the primary cabinet.

2. Install powered BiCoder boards (typically 48 zones per cabinet) in additional enclosures near the primary cabinet.

3. Run a short two-wire path from the BaseStation to the first additional cabinet, connecting to the two-wire terminal on the powered BiCoder board.

4. Continue the two-wire path from the first additional cabinet to the next, and so on, daisy-chaining all cabinets together.

This approach allows you to utilize nearly all 200 zones of a BaseStation 3200's capacity using conventional wire, even when physical space limitations prevent mounting all the boards in a single cabinet. The two-wire path between cabinets facilitates all communication and control without requiring you to physically relocate or consolidate the conventional wire bundles.

Wireless Connection Between Cabinets

If you cannot run a two-wire path between cabinets—for example, when they are too far apart or separated by obstacles—you can use a SubStation to create a wireless connection. The SubStation was specifically developed for scenarios where powered BiCoder boards need to be installed in remote locations without the ability to run a physical two-wire connection back to the BaseStation controller.

Retrofit Applications Using Existing Infrastructure

One of the most cost-effective applications of powered BiCoders is retrofitting existing conventional controller systems. This approach allows you to preserve and reuse the existing infrastructure while upgrading to modern technology.

In a typical retrofit scenario:

1. Replace one existing controller pedestal with a BaseStation 3200.

2. In each remaining pedestal, remove the old controller faceplate and circuit boards.

3. Install a powered BiCoder board into the existing controller tray.

4. Connect all existing zone wires from the sweeps in each pedestal to the terminals on the powered BiCoder board.

5. Power each powered BiCoder using the existing transformer already installed in that pedestal.

6. Run a two-wire path between pedestals to connect all powered BiCoders back to the BaseStation.

This method preserves the existing stainless steel pedestals, concrete pads, transformers, grounding systems, and all field wiring. Because the existing zone wires are typically numbered, you can maintain the same zone configuration from the previous system, or you can rearrange zones in any order you prefer using the search and assign function.

The cost savings can be substantial. A project that might cost $70,000 to install completely new infrastructure can often be retrofitted for approximately $7,000-$12,000—roughly 10-15% of the new installation cost.

Pedestal Conservation Kit (PCK)

For pedestal retrofit applications, a specific powered BiCoder model called the Pedestal Conservation Kit (PCK) is available. 

This kit includes:

• A powered BiCoder board
• A power cable for transformer connection
• A backing plate with standoffs for mounting
• Installation hardware including a drill bit and cutting oil

The backing plate is essential because standard powered BiCoders have exposed solder connections on the back. The backing plate with standoffs prevents these connections from contacting the metal cabinet, which could cause shorts or other electrical problems. This design allows the board to be safely mounted in plastic cabinets, stainless steel enclosures, painted steel boxes, or any other cabinet type.

The kit provides nearly everything needed for installation, requiring only basic contractor skills to properly mount and secure the board.

Serial Numbers and Addressing

Powered BiCoder boards have unique serial numbers that make them addressable just like any other BiCoder in the system. While standard two-wire BiCoders have serial numbers starting with D, E, or Q (for single-zone, two-zone, and four-zone BiCoders respectively), all conventional wire powered BiCoders have serial numbers beginning with VA or VB.

Each screw terminal on a powered BiCoder board has a specific address. For example, a board might have serial numbers ranging from VAH-3901 through VAH-3924 for a 24-zone board. The serial number label is typically affixed to the board for easy reference.

An important feature of the addressing system is that you can assign zones in any order you want—you are not locked into the physical sequence of terminals on the board. During the search and assign process, you can reorder zones to match your preferred irrigation sequence, group zones by hydrozones, or organize them to correspond with soil moisture sensors.

This flexibility means you can reorganize your zone structure without physically moving any wires. Simply reassign the zones in the controller interface to achieve the desired order. However, it is strongly recommended to take detailed notes during this process, as it is easy to lose track of which physical terminal corresponds to which zone number if you deviate significantly from the board's physical layout.

Master Valve and Extra Zone Terminals

Powered BiCoder boards include additional terminals beyond the standard zone count. These extra addresses (typically labeled VE or similar) provide two spare connections per board. A 24-zone board actually provides 26 addressable terminals.

These extra terminals are commonly used for:

• Master valve connections
• Pump start relays
• Additional zones when you need just one or two more than the standard board capacity

For example, if you have 25 zones to convert, you only need one 24-zone powered BiCoder board because the two extra terminals provide the additional capacity.

Connecting Two-Wire Devices

The two-wire terminal on a powered BiCoder serves multiple purposes beyond extending two-wire paths for additional zones. 

This terminal is also used to connect two-wire communication devices to the system, including:

• Pressure sensors
• Precipitation sensors
• Flow sensors
• Additional moisture sensors beyond the four that can connect to the A1, A2, B1, B2 terminals

When working with conventional wire systems, it can be helpful to refer to the two-wire terminal as the "communication port" or "com port" if you are not using it for additional zones. This clarifies that it is the connection point for any device that needs to communicate data back to the controller.

In some cases, you may need to run a dedicated section of two-wire to bring these communication devices into your system, especially if they are located far from the controller or powered BiCoder board.

Common Wire Management

When converting a conventional system that previously had multiple separate controllers, each with its own common wire, it is critical to maintain proper common wire separation. You cannot cross or connect commons from different wire bundles or different transformers.

Best practice is to keep each conventional wire bundle's common wire isolated to its own powered BiCoder board. Wire up the commons from each bundle to their respective board, and do not connect commons between boards. The two-wire path connecting the boards back to the BaseStation facilitates all necessary communication and management without requiring common wire connections between boards.

Crossing commons can create shorts, equipment damage, or a complete system failure. If you are unsure about common wire paths in an existing system, trace each common back to its source transformer before making connections.

Troubleshooting Wire Corrosion Issues

Black corrosion on conventional wire can potentially inhibit connections to soil moisture sensors. Whether it actually causes problems depends on the severity of the corrosion.

In many cases, the sensor will still be detected during search and assign, but data transmission may be compromised. The corrosion might exist at one splice or accumulate across multiple splices, with the effects compounding over the wire run.

The most frustrating scenario is intermittent communication, where the sensor works sometimes but not consistently. This can be difficult to diagnose because the problem is not constant.

If you are unable to detect a moisture sensor during search and assign, and you suspect wire corrosion, inspect all splices in the wire path between the sensor and the powered BiCoder board. Look for black discoloration on the copper when you strip back the wire insulation. Cleaning or replacing corroded sections may resolve the communication issue.

Video Walkthrough

Video originally published May 2021.

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