TAP Communication Cable Guide

This article discusses the requirements for the data cable that connects the TAP (or Gateway), to the Data Logger (CCA, Cloud Connect or MMU).

Contents: 

1. TAP Communication Cable Requirements
2. Recommended Cable Types
3. Maximum Cable Length Recommendations
4. Using Ethernet Cables (Cat 5 / Cat 6)
5. Installation Tips!

TAP Communication Cable Requirements

Tigo's TAP and Gateway serve the same function. The TAP is just the latest version. To identify which device you are using, see TAP vs Gateway (as Gateways use a slightly different connection method)

The TAP (or Gateway) on the roof, requires a 4-Lead data communication cable with at least one Twisted Pair (TP) to connect with the System's Management Device (Data Logger). This cable must be RS-485 comparable (low capacitance and/or shielded), and protected from the elements.  

The data communication cable must have these features:

• At least 1 Twisted Pair (TP) of wires (for added data-shielding of the A and B leads)
• Min wire size of 22 AWG (0.33 mm²) if more than 1 TAP is connected
• Max cable Outside Diameter (OD) of 0.35 inches / 9 mm (so it will fit inside the cable gland)

Recommended Cable Types

Tigo recommends using a 4-lead RS-485 style, or multi-lead Ethernet (Cat-5) Cable. These cables  usually include at least one Twisted Pair (TP) and are manufactured in 2 types:

• UTP - Unshielded Twisted Pair 
• STP - Shielded Twisted Pair 

Either cable type can be used, but STP cable is highly recommended if the wiring is not housed in conduit and/or located near an HVAC electrical motor or radio broadcast equipment. Anything that can create a strong electromagnetic field can cause interference on a non-shielded cable and this will affect the data signal. 

If your cable is not housed in a conduit, please use an outdoor-rated (UV resistant) sheathed cable for weather protection. 

Lastly, remember to check with your Authority Having Jurisdiction (AHJ) to see if there are any local requirements for cabling within your community.

Maximum Cable Length Recommendations

The length of a cable can greatly affect its resistance (especially if Unshielded UTP is used). The table (below) provides the maximum length recommendations for data communication cables, based on the wire gauge and the number of TAPs.

Wire sizes are listed in American Wire Gauge (AWG) and Millimeters (mm).
Wire Lengths are listed in Feet (ft) or Meters (m). 

Using Ethernet Cables (Cat 5 / Cat 6)

Multi-lead cable (like Cat 5 / Cat 6) may require that the installer combines wire Pairs and/or Triplets. Here are some guidelines for Ethernet cable usage that will help maintain a quality signal and deliver full power to all the TAPs on the system. 

1. Use 1 Twisted Pair for the A and B wires. These wires must both be from the same pair, not from different pairs.
2. To reinforce the 24V DC Power send, combine duplicate pairs or triplets of the remaining leads.
   (This can be helpful for distances over 100 feet, or on systems with 2 or more TAPs.)

Note: For commercial systems, using Ethernet cable is strongly discouraged due to the longer cable lengths combined with the number of TAPS per cable. For these reasons, Ethernet (Cat 5 / Cat 6) cables may not meet the minimum requirements for interference and distance.

STEP 1. Remove 1.5in/3cm of the outer rubber sheathing, to expose the internal wires.   Be careful to not nick or damage the insulation on the internal wires. If damage occurs, cleanly cut the cable-end, and start again
STEP 2.  Open the TAP and identify the terminal block that will receive the CCA connections.   The Red Arrow is pointing at the incoming conductor terminals (notice it does not have a resistor installed between A and B terminals).   If you experience difficulties accessing the terminals on the TAP, please review our article on Opening and Closing the TAP.
STEP 3.  Remove (or lift) the Terminal Connector   Using a flat head tool or blade, insert just underneath the Terminal and gently rotate it clockwise, and counter clockwise, until it loosens from the board.
STEP 4. Unscrew the Cable Gland at the bottom of the TAP, and feed the cable through. This can be done before or after you have removed the outer sheathing (STEP 1).
STEP 5.1 (Terminal Method) Strip the wires and connect them to their specific posts, by unscrewing the terminals and inserting the wires into the terminal brick.  Make sure there is no exposed copper outside of the terminal housing, and the color-coordinating wires match the other end (at the Data Logger).  When you have completed attaching the wires, center and press the terminal back down onto the pins (located on the TAPs board).
STEP 5.2 (IDC Method) Connect the unstripped wires to their specific posts, by using the Insulation-Displacement Contacts (IDC) to quickly seat the wires, without having to trim the vinyl.  Using an IDC Punch Down Tool or small flat-head screwdriver, push only 1 wire into each of the IDC terminals.  Note: Since the IDC connector cannot take multiple wires, the maximum wire length is affected. This method also supports a maximum of 2 TAPs.
STEP 6 Tighten the Cable Gland, by twisting it clockwise (righty tighty). Make sure it's firmly tightened, to prevent water entry. Then, close the TAP, and attach to the frame of a module with Cable Glands facing downward (to discourage water from following the cables, into the Glands).

Installation Tips!

Conduit and Cable Trays: 

When running the communication cable in the same conduit as an energized PV String Wire (home-run lead), use a cable that has a 600 VDC insulation rating. This will eliminate the need for the installation of a separate conduit for the communication cable, especially in systems where the string voltage will never exceed 600 VDC.

When installing multiple TAPs (or for longer distance runs):

Combine the maximum amount of wires (from the Data Communication Cable), into the power leads to the 24V DC Power send. For Ethernet cable (Cat 5 / Cat 6) this will be 3 individual wires for each post. 3 for the "+" (positive), and 3 for the "-" (negative). 

NOTE: This will only work when using the screw terminal brick as a connector, because multiple wires cannot fit in the punch-down IDC terminals.

A resistor is pre-installed on the right-hand side terminals on each TAP. It is connected to the A and B terminals, which are the RS-485 data signals. Remove the resistors from the multiple TAPs along the daisy-chain. When you get to the last TAP in the chain, it must have the resistor inserted in the outgoing A and B terminals.

Mounting the TAP:

The TAP is designed to be installed under a panel, not out in direct sunlight. Tigo recommends installing the TAP on the frame of a panel, not in an attic or other radio signal decreasing barrier.

The TAP connects to the PV-Module frame using the mounting bracket. Mount the TAP with the label side outward (facing away from the panel). If the PV-Module has no frame, the holes of the brackets can be used to screw them to a panel racking system.

The signal radiates horizontally to the sides, not towards the sky or ground, so install it near the center panel of the array whenever possible.

For full installation directions, see page 12 of the TAP Installation Manual.

Testing the TAPs: 

After installation is complete, the Discovery portion of the commissioning process should find all of the TAPs, quickly. If the Discovery reports fewer TAPs than configured on the Equipment page, run a Gateway Test. You can do this by using the Tigo Energy Intelligence App installed on your phone/device. See section #3 Confirm Network.

For legacy equipment (Tigo Cloud Connect and MMU), you can do the test using the buttons on the control panel for: 2.5. Gateway Test. https://support.tigoenergy.com/hc/en-us/articles/208746708-Cloud-Connect-MMU-Menu-Reference