Q: What is the voltage input for the RMU3-B?

The PWR IN operating voltage is 9 to 18 volts AC (50/60Hz) or 9 to 22 volts DC. CSA/UL requires a class 2 energy limited power source. Our custom power transformer available from Mobiltex has a breakdown voltage of 5000VRMS for improved lightning immunity (typical is only 1500VRMS). Mobiltex Part Number: T01A42TR201

Q: Can I use the rectifier taps to power the RMU3-B?

No. It is not recommended due to less electrical isolation. CSA/UL installations require a class 2 energy limited power source. Power your RMU3 from the AC mains with our custom transformer available from Mobiltex which has breakdown voltage of 5000VRMS for improved lightning immunity (typical is only 1500VRMS). Mobiltex Part Number: T01A42TR201

Q: Do I connect one wire from the RMU power transformer to earth/functional/chassis ground?

No. Select the two appropriate color of wires required for your input voltage. Cap off the unused wires individually.

For example, when using the TR20VA020 Transformer (Mobiltex Part Number: T01A42TR201):
120VAC: Connect the black and white wires across the hot and neutral 120VAC lines
240VAC: Connect the black and orange wires across the hot 240VAC lines

Q: What does a flashing green LED on the RMU3-B indicate?

When the multi-purpose LED is flashing green, it will depend if the device was recently transmitting:

  • If the RMU3 recently transmitted, the flashing green LED indicates it is waiting for an acknowledgement from CorView. Once the RMU3 receives the acknowledgment, the green LED will turn solid green.
  • If the RMU3 is not transmitting, the flashing green LED indicates that the most recent reading is outside of the programmed measurement limits (alarms)

Q: When the RMU3-B loses power, does it send an AC failure alarm right away?

By default, the RMU3-B will wait for 1 hour before sending an AC failure alarm to prevent nuisance alarms during short power failure events. When AC power is restored, the RMU3 will wait for 5 minutes before sending a clear exception report. These holdoff periods are programmable when the RMU3 is initially configured (Note: avoid short hold-off times to prevent nuisance alarms and excessive data transmissions). If the AC Sense is disabled during configuration, the RMU3 will ignore all AC faults. The RMU3-B reports both AC & DC power input failure as a loss of AC power.


Q: What is the difference between an RMU3-S and RMU3-G antenna?

The RMU3-S is the satellite communications variant of the RMU3. The RMU3-G is the cellular antenna.

Q: Which cellular network does the RMU3-G antenna utilize?

AT&T in the USA, Rogers in Canada. Cellular provider coverage maps can be used to ascertain if your sites have cellular coverage.

Q: The RSSI (Receive Signal Strength Indicator) is different each time my RMU3-S reports in. Is this normal?

Yes, this is normal. The satellites the RMU3-S utilizes are in-motion orbiting around the earth. When the satellite is directly above the antenna, it will report a strong RSSI. If the satellite is low on the horizon when the RMU3 transmits, a lower RSSI is possible. The RSSI will change throughout the day as the satellite constellation moves through its orbit.

Q: Should I point my RMU3-S South?

No. Orient the antenna so that the CorTalk logo is facing up toward the sky. Ensure the antenna has an unobstructed clear view of the sky. Building overhangs, pipe racks and dense large trees may affect satellite transmissions.

Q: I have 9 locked GPS satellites in-view. Why is my RMU3-S not communicating with the satellite network?

The RMU3-S utilizes two satellite networks. The GPS network is used strictly for Geo-location and accurate interruption timing. The RMU3-S utilizes the Iridium satellite network for data communication. The Receive Signal Strength Indicator (RSSI) will give you a rough idea of the communication satellite coverage.

Q: How long can the cable be between my RMU3-B and RMU3 antenna?

The interconnect cable may be extended up to a maximum length of 24 meters (78 feet) by screwing together extension cables.

Q: How often should my RMU3 antenna be charged if I’m putting it in storage?

If the RMU3 is not powered on while in storage, we recommend recharging the batteries at least once every 6 months. The backup batteries can be recharged by connecting the antenna to an RMU3-B base that is powered on.

Q: How long does it take to charge the batteries in an RMU3 antenna?

It takes about 4 hours, but overnight is recommended if the batteries were completely drained.


Q: My Solid-State Relay (SSR) is not interrupting.

Q: My Solid-State Relay (SSR) is not interrupting.

  • The SSR that Mobiltex supplies is AC only and requires minimum voltage of 24VAC at terminals 1 and 2. If interrupting on the secondary side of the rectifier, ensure there is at least 24VAC. If not, consider interrupting on the primary side.
  • The control terminals 3 and 4 are polarity sensitive:
    • Pin 3 is positive (+)
    • Pin 4 is negative (-)
  • Ensure the RMU3 has adequate power on the PWR IN terminals.
  • The INT pins should toggle between 0 – ~18VDC while interrupting.
  • Confirm that the RMU3 has a GPS time lock. The RMU3 can take up to 12.5 minutes to acquire a full GPS time lock on initial startup.
  • Ensure you have configured the RMU3 for a normally open (N/O) relay.

Q: How many relays can I connect to a single RMU3-B?

It depends on the relays you are using. The RMU3-B will supply up to 750mA total driving current for relays. A typical SSR will use 7-12mA per SSR relay. For mercury relays, we recommend using only one 100A relay (Mobiltex PN: K07111NC12D), or two 60A mercury relays (Mobiltex PN: K07111060NC).

Q: What relays can I use to interrupt DC side of the rectifier?

The Mobiltex DCR is perfect for DC interruption up to 100V and 100A (depending on the model). Mercury relays can also be installed on both the AC or DC sides of the rectifier.


Q: I’m getting a “Failed to Ping RMU3” error when connecting to the RMU with my RMU programmer.

For PC based configuration:

  • Ensure the RMU3 base is adequately powered (9 to 18 volts AC or 9 to 22 volts DC).
  • Confirm both the antenna and the base are connected to the programmer.
  • Check that the Link Port in RMU3 Configuration Editor is set to “USB”.
  • Be sure there are no other configuration or firmware programming software running in the background on your PC.
  • Ensure that the programmer drivers are installed on your PC.
  • If RMU3 antenna has been in storage for a long period of time, let it charge for a while. The battery level may be low causing high current consumption and interfering with normal operation.

For mobile device configuration (RBT connection):

  • Ensure the RMU3 base is adequately powered (9 to 18 volts AC or 9 to 22 volts DC).
  • Confirm both the antenna and the base are connected to the programmer.
  • Connect to the RBT through the config app. Do not connect to it through your mobile device’s Bluetooth settings.
  • Try tuning the Bluetooth off and on again on your mobile device.
  • Try forgetting or unpairing the device in your mobile device’s Bluetooth setting.
  • Make sure no other mobile devices are already connected to the RBT.
  • Try reinstalling the config app on your mobile device.

Q: Can I configure my RMU3 at the office before travelling to a site?

Yes. You will need to know the site specifics such as shunt value, interruption relay type and any alarm levels.

Q: Can I configure an RMU3 remotely?

Interruption schedules can be set remotely via the CorView web interface. Users that subscribe to premium CorView features can remotely adjust the RMU alarm limits and change the interruption cycle order (On First Vs. Off First). The measurement type, shunt scaling factor, and relay type etc. must be configured locally.

Q: Can you tell what the shunt scaling factor is for the RMU3 remotely? Can you change it remotely?

Unfortunately, No. The shunt scaling factor can only be viewed and programmed locally with an RMU programmer.

Q: Should I check the “Sync to AC line” box?

For sites with single phase AC power: Yes, check Sync to AC line. For sites with 3 phase AC power: No, do no check Sync to AC line.

Q: I see numerous instances of the fault “Communications failure with RMU3 base” in the RMU3 Configuration Editor.

This error is normal and common to see in the fault history. When you disconnect the base and antenna during installation and configuration, it breaks the communication link and generates this fault.

Q: I am replacing only an antenna at a site, do I have to reprogram the antenna?

Yes. The RMU3 configuration programming is stored in non-volatile memory in the antenna. The new antenna will need to be configured to match the antenna it is replacing.

Q: I am replacing only the RMU3-B base at a site, do I have to reprogram it?

No. The RMU3 configuration programming is stored in non-volatile memory in the antenna. Replacing the RMU3-B will not affect the configuration.


Q: I made a mistake in my interruption schedule that has been sent to the RMU3, how do I correct it?

Resend the correct schedule. The RMU3 will only remember the most recent interruption schedule it has received.

Q: How do I cancel an interruption schedule I already sent an RMU3?

Send the RMU3 a Rectifier On command via CorView.

Q: Why does the font color of “INT” change under RMU3/5 Rectifier Status column in CorView?

There are three different interrupting states based on the relay validation test (see next question)

CorView Status: Interrupting and relay validation not performed (black text)The rectifier is currently interrupting. Relay validation was not performed.
CorView Status: Interrupting and relay validation passed (green text)The rectifier is currently interrupting. Relay was checked and passed.
CorView Status: Interrupting and relay validation failed (red text)The rectifier is currently interrupting. Relay was checked and failed.

Q: Why is the RMU3 bubble showing up in the middle of the ocean on the CorView map?

The RMU3 has not acquired a GPS position lock yet. Once it gets a GPS position lock, it will correct its location with the next power up message.

Q: What is the Rectifier AC Volts column in CorView?

It is the AC ripple voltage on DC output of the rectifier.

Q: What is Relay Validation?

The RMU3 performs a relay validation test when starting scheduled interruption. The RMU3 uses the programmed lower Rectifier DC current limit as a threshold to confirm that the relay is opening and closing. If the lower limit is not programmed or the Relay Validation Enable box is not enabled, relay verification will not be performed. If you send an interruption schedule and it starts in the past, the RMU3 will skip the verification test.

Q: I am replacing an RMU3 (both base and antenna or antenna only) at a site. What do I need to do in CorView?

In order to maintain data continuity and historical readings, you must replace the old ESN with the new ESN. (Note: Only CorView Administrators can perform this task)

After installing, configuring and powering up the new antenna, follow the steps below:

  1. Log into CorView.
  2. Select [SETUP] – [Site List].
  3. Find the auto-created site. The site name will be the ESN of the new antenna.
  4. Delete the auto-created site. NOTE: you will lose any readings the new antenna has already sent.
  5. Find the existing site with the old antennas ESN assigned to it.
  6. Click on the pencil icon to edit the ESN assigned to the site.
  7. Select the new ESN from the RMU ESN drop-down list.
  8. Click the Update button at the bottom of the page to save your changes.
  9. Perform a button press on the RMU3 or a Readings Request in CorView to send a message to CorView.

If the ESN is reassigned in CorView before the antenna is physically changed, you can skip steps 1 through 4.

Q: I changed out an RMU some time ago and now have two sites with readings. Can I merge old readings and new readings?

Unfortunately, No. After a significant amount of time has passed, the sites cannot be merged. The old site can be marked as not active in Site Setup to prevent overdue alarms and emails.


Q: My RMU3 reports that relay validation always fails, but when I go to the site it is interrupting?

Check that the lower limit programmed for the Rectifier DC current is not 0 amps. The relay validation test checks if the current is less than the lower limit when the relay is open.

Q: My RMU3 readings are fluctuating but when I check at the site with a meter everything seems fine?

Check for connection issues such as poor crimps, loose screws, corrosion on connections and damaged wires. Consider deploying a data logger to confirm the readings. The RMU may be catching intermittent issues that were not previously found with monthly visits.

Q: My RMU3 is reporting as Overdue.

CorView knows when the RMU should be sending measurements but did not receive them. There are numerous possibilities for missed transmissions:

  • Check that the antenna is activated on the communications network. This can be found in CorView under [SETUP] – [RMU List].
  • Check for physical damage at the site.
  • Confirm the RMU3 is powered on. (9 to 18 volts AC or 9 to 22 volts DC).
  • Ensure that RMU3-G cellular antennas are in an area with good cellular coverage
  • Confirm that RMU3-S antennas have a full unobstructed view of the sky. Check for building overhangs, dense trees etc…
  • Use your RMU3 programmer to read out any faults it has detected.

Q: My RMU is reporting “Over Range” for all readings and extremely high temperature.

Check for a loose or damaged connection cable between the base and antenna.

Q: My RMU3 keeps sending power up messages.

This is due to the RMU3 losing power. There are a few items to check:

  • Check for a loose or damaged connection between antenna and base.
  • Confirm the RMU3 is adequately powered (9 to 18 volts AC or 9 to 22 volts DC).
  • Deploy a datalogger on the power input to check for power fluctuations.
  • If the antenna has been in storage for a long period, the batteries may need to be charged.


Q: I am still having issues, how can I get tech support?

Call or email our tech support team. They can be reached toll free at 1-844-689-3282 – ask for Service. They can be emailed at service1[at]mobiltex[dot]com.


Call toll free: 1 844 689 3282 [NA]
1794 340515 [UK]

Our industry-leading Sales, Technical Support, and Service teams are ready to take you from product selection to initial set-up and continue to provide dedicated support throughout the product lifecycle.