MPG-2 Wireless Meter Pulse Generator (con't)
6.0 Operation
6.1
Communication LEDs
Upon power-up, the YELLOW comm LED should light indicating that the Zigbee dongle is enumerated, correctly initialized
and communicating with the MPG-2's processor. Within about approximately 45 - 60 seconds, the GREEN comm LED will
blink each time a valid transmission is received from the meter. As long as valid transmissions are received by the dongle
and successfully relayed by the MPG-2's processor, the Green comm LED will blink about once every 8-9 seconds. If the
Green comm LED does not blink, that is an indication that the data transmissions from the meter are not being received,
may be corrupted, or in some manner are not valid transmissions. If the Green comm LED has been blinking reliably for
some time, then stops for a while and then restarts again, this indicates that transmissions are intermittent and sporatic, or
generally means there is a problem in the dongle's ability to receive data reliably from the meter. To correct this, change
the proximity of the MPG-2 to the meter, move it closer to the meter if possible and eliminate any metalic obstructions
between the meter and the MPG-2. Also check to make sure that any walls or barriers between the MPG-2 and the meter
have as little metal in them as possible. For the longest distances you must have line-of-sight.
6.2
Pulse Outputs
Outputs can be configured to be in the
Toggle
(Form C) mode or the
Fixed
(Form A) mode. Generally speaking, the
Form C mode can be used with either 2-Wire or 3-Wire Pulse receiving devices, while the Form A mode uses only a 2-
Wire interface to the downstream (receiving) pulse device. The choice would depend on the desired pulse format that the
receiving device prefers to see.
If the dongle is reliably receiving data from the meter and passing it on to the MPG-2's processor, then you should see the
Red and Green output LED's toggle each time the selected pulse value is reached, and the MPG-2's processor generates
a pulse. If the pulse output value is too high and pulses are too slow, then select a lower pulse value using the
programming port and the SSI Universal Programmer program or a terminal program (See Page 6).
If pulses are being generated too rapidly, select a higher pulse output value. The maximum number of pulses per second
is approximately 10, which means that the output's open and closed times are about 50mS each in toggle mode. If the
calculation by the MPG-2's processor for pulse output timing exceeds 15 pulses per second, the MPG-2 will light the RED
comm LED, indicating an overflow error, and that the pulse value is too small. The LED is "latched" on so that the next
time you look at it this RED LED will be lit, and you will have a indication that an error has occurred. The operation of the
MPG-2 will continue even though some pulses were lost. In this way, you can quickly determine if a pulse output value is
too small, and thus, pulses too fast at a high demand. However, in the optimum application, pulses would not exceed
more than one pulse every 2 seconds, with a 1 pulse per second maximum. This allows a very even and "normal" pulse
rate that as closely as possible resembles an actual KYZ pulse output from the meter.
The MPG-2 will "spread out" the pulses over the next 7 second period if a high enough watt-hour value is received in a
transmission to require that more than one pulse is generated. For example, suppose you have the Output Pulse Value of
10 wh selected. The next 8 second transmission yields 24 wh have been used. Since 24 watt-hours exceeds the 10 watt-
hour setting, two pulses must be generated. The first 10wh pulse will be generated immediately. About three seconds later
the second 10wh pulse will be generated. The remainder of four watt-hours stays in the accumulated energy register (AER)
awaiting the next transmission and the energy value of that transmission to be added to the contents of the AER. Another
example: Assume 25 wh/p Output Pulse Value. Let's say the next transmission is for 130 watt hours. 130 is greater than
25, so 5 pulses will be outtputted over the next 7 seconds, approximately one each 1.4 seconds (7 seconds / 5 = 1.4
seconds). The remainder of 5 wh will stay in the AER awaiting the next transmission. Some trial and error may have to be
done for any particular building since pulse rates will change depending on maximum load. The larger you can make the
pulse value the more regular the output pulses from the MPG-2 will be.
5.3
Overranging the Output
As mentioned above, if there are too many pulses calculated to be outputted in a 7 second interval than the MPG-2 can
generate given the timing constraints, the MPG-2 will light the RED comm LED. In this situation, simply increase the pulse
output value using the programming port, and cycle power to the MPG-2 to reset the RED comm LED. This is intended to
notify the user that a higher pulse value is needed. As load is added to a building over time, there is some likelihood that
this will occur so be sure to consider this if/when you add load to the building. If an error condition occurs, set the Pulse
Value to a higher pulse value, for example double the current value. Remember to change the pulse constant of your
receiving device as well, since pulses will now be worth a higher watt-hour value. Cycle power to the MPG-2 to reset the
RED comm LED after increasing the pulse value.
