How Do I Troubleshoot a Communicator Trouble on a DSC NEO?

To troubleshoot an issue between a DSC NEO panel and a TL880 communicator, there are several points that you will need to check. It is best to begin at the panel and work your way out to the TL880, checking voltages at each location. You will need a volt meter set to the 20 Volt DC scale.

The TL880 style communicators come in an AT&T and a Verizon version. They connect to the DSC PowerSeries NEO panel via the PCL-422 board on the PC Link 2 connector at the top of the panel board. If the DSC NEO isn't recognizing the communicator, there are a number of things you can check to determine whether the issue could be the panel, the cables, the PCL-422, or the communicator itself.

Follow the steps below to troubleshoot:

1. Check programming: Before you bring out the volt meter, verify that the panel programming is correct. If programming isn't properly set, the NEO panel won't know that it's supposed to be communicating through the radio.
   • Enter [*] + [8] + Installer Code (default is 5555) to enter panel programming.
   • Go to field [015] and set Option 7 (Telephone Line Monitor or TLM) to OFF.
   • Go to field [382] and be sure Option 5 is Enabled.
   • Go to field [300] and be sure Option [001] is set to Alt Comm Auto
   • Go to Field [380] and be sure Option 1 is Enabled.
   • Go to Field [301] and be sure Option 1 is set to DCAA
   • Go to Field [350] and set the format to Contact ID or SIA. The correct setting here will depend on your central station. Alarm Grid customers choose Contact ID which is an entry of 03 for receiver 001. The default value for all receivers is SIA (04).
   • Finally, verify that you can access Field [851] for Interactive Services. This indicates that the panel is set up properly for the Alarm.com capable radio.
2. Verify wiring: Make sure the PCL-422 cable is connected to PC Link 2, not PC Link 1 at the top of the panel board. The cable that connects the panel to this board has a RED wire. The red wire should be toward the right when connected properly.
   
   
   At the PCL-422, the connector will have the RED wire on the side closest to the terminal block when properly connected.
   
   
   PCL-422 Terminals:
   
   
   
   TL880 Communicator Terminals:
   
   
   The wiring connections between the PCL-422 and the TL880LECVZ N or TL880LEAT N are as follows:
   

   PCL-422 Terminal	TL880 Terminal
   +12V	+12V
   GND	GND
   TX(+)	RX(+)
   TX(-)	RX(-)
   RX(+)	TX(+)
   RX(-)	TX(-)

   In the above wiring scenario, the TL880 gets power from the PCL-422, which gets power from the DSC NEO Panel. The nominal current draw of the TL880 is 150mA, however, during a cellular transmission, the current draw can quickly spike to 400mA. If this current draw is too much based on the devices connected to the panel, the communicator can be powered by an HSM2300 or HSM2204 power supply module instead.
3. Verify voltages: Once you verify that all of the above programming and wiring is correct, if the DSC NEO and the communicator are still not communicating with one another, it's time to begin checking voltage at various points. Begin by checking voltages at the PC Link 2 pins, and work your way out to the TL880 until you find the issue.
   
   A quick note about how to properly use a meter. Be sure that the black lead for the meter is connected to the COM or Common port. You may have to choose a scale, as well as AC or DC voltage or your meter may auto-range, meaning it determines the scale automatically. For our purposes, a 20 Volt DC scale is what should be selected, if necessary. If you don't have a multimeter, you can probably find an inexpensive one at the hardware store, home improvement store, or in most places where electronics are sold.
   
   
   
   Be sure Step 1 is completed prior to checking voltages. If the programming isn't properly set, these voltages may not be accurate.
   
   While checking voltages, the Black meter lead will stay on keypad GND, and only the Red meter lead will change locations. Proper PC Link 2 voltages:
   
   

   Black Meter Lead	Red Meter Lead	Voltage Expected
   Keypad GND	Pin 5 (Far Left)	~11.9VDC
   Keypad GND	Pin 4	~3.3VDC
   Keypad GND	Pin 3	0VDC
   Keypad GND	Pin 2	Less than 1VDC (~.2VDC)
   Keypad GND	Pin 1 (Red Wire Pin)	~13.7VDC

   
   If the voltage at the PC Link 2 pins is good, plug the cable into the panel with the Red Wire toward the right. Now, perform the same meter readings, but at the end of the cable that connects to the PCL-422. In the image shown below, with the cable connected to the PCL-422, you can see small, square metal tabs located within the plastic cable header. You can use these points to meter voltages once the cable is connected to the PCL-422. Prior to making the connection, you may be able to meter within the pin holes themselves, but if not, use the same metal tabs.
   
   Perform the same meter readings as shown in the table above. First, meter with the cable disconnected from the PCL-422, and assuming voltages are basically the same as what you saw on the PC Link 2 pins, connect the cable to the PCL board and meter again. There should be no significant change in voltage.
   
   
   
   Next, you can check Power and Data voltages between the PCL-422 and the TL880 Communicator.
   
   

   Meter Lead Placement and Voltage Expected At the PCL-422

   Black Meter Lead	Red Meter Lead	Voltage Expected
   PCL-422 GND	+12V	~12.47VDC
   PCL-422 GND	RX(-)	~0.46VDC
   PCL-422 GND	RX(+)	~3.98VDC
   PCL-422 GND	TX(-)	~0.29VDC
   PCL-422 GND	TX(+)	~3.42VDC

   Meter Lead Placement and Voltage Expected at the TL880 Communicator

   Black Meter Lead	Red Meter Lead	Voltage Expected
   TL880 GND	+12V	~12.37VDC
   TL880 GND	RX(-)	~0.29VDC
   TL880 GND	RX(+)	~3.41VDC
   TL880 GND	TX(-)	~0.46VDC
   TL880 GND	TX(+)	~3.98VDC

Summary:

• We determined these voltages by checking our working system. Due to variations in volt meters and electrical wiring within a protected premise, the readings you see may differ slightly from ours. Consider a difference of more than 1.5VDC to be significant.
• If the voltages at the PC Link 2 pins are not what they should be, verify programming again. If the programming is correct, the problem could be the panel. Try powering down, removing the panel from the metal cabinet, then powering back up and checking voltages again. It is possible for some metal on the printed circuit board to touch the metal cabinet and cause issues. If you do this and the voltages are still incorrect, contact your dealer/distributor to verify if the panel is bad. DSC may require a case number from their technical support team before they will warranty replace a panel.
• If the PC Link 2 voltages are good, but voltages at the opposite end of the connector cable are bad, replace the cable between the panel and the PCL-422.
• If the panel pins and the cable check out, but the voltage becomes irregular once the cable is connected to the PCL-422, verify that the PCL-422 is mounted using the nylon standoffs provided. This will ensure that the back of the PCL-422 is not touching the metal cabinet. If this board is properly installed, but the problem persists, contact your dealer/distributor to determine if a warranty replacement is in order.
• If everything is good at the PCL-422, but voltages become irregular once you connect the TL880, then the communicator may be the issue. Make sure that nothing metal could possibly be touching the back of the TL880 printed circuit board. Assuming there isn't, contact your dealer/distributor to determine if a communicator replacement is in order.