Reed FDM Applications
- Oliver Skidmore (Unlicensed)
The "Reed FDM" VTi21 variant is related to the "Reed Relay" firmware, however the FDM monitor supports a different and larger list of frequencies. The VTi21 can be used to monitor the in-band electrical current amplitude of certain Reed frequencies / channels.
The set supported depends on which firmware variant is selected. Contact mpec for more information.
RFDM | FDM2 | FDM3 | |||
|---|---|---|---|---|---|
Channel | Frequency | Channel | Frequency | Channel | Frequency |
F04 | 803.25 Hz | F20 | 682.50 Hz | F15 F18 F39 F40 F41 F42 | 706.50 Hz 692.00 Hz 488.50 Hz 483.00 Hz 478.50 Hz 473.50 Hz |
The VTi21 implements very narrow-band filters to determine the amplitude of the current at these frequencies, with a 2.5 Hz bandwidth.
The effect is an output signal that is illustrative of the logical state of that channel/frequency. All out-of band noise is rejected. Any deviation in frequency or level in the received signal will result in a drop in the output amplitude.
The system may be fitted on both transmitter and receiver. As both systems exhibit the same current range.
The output rate of the system is 3 samples per second on each channel.
SA380TX Configuration
4-20mA Output:
The Reed FDM monitor outputs the total current in the frequency range over the 4-20mA interface, however on its own this output is of limited use.
RS485:
For information on the wiring required for RS485 communications please see VTi21 Hardware Wiring for RS485 Operation and follow the instructions titled "Wiring for RS485 Operation" or "Alternate Wiring for RS485 Operation" dependant on the SA380TX's hardware configuration.
To configure the VTi21 over RS485, please follow the instructions under the heading "Configuration on RS485" in the VTi21 Configuration guide.
After configuring the RS485 connection, each reported channel needs to be assigned to an analogue channel as per the example shown below.
Installation
The conductor(s) carrying the signals to be monitored must pass through the current transducer connected to the "CH1" input on the VTi21. In this application "CH2" is redundant. The conductors can pass through the current transducer in either direction.
Reed VTi21 Outputs
The Reed VTi21 sensor can output the following quantities when monitoring Reed receivers.
VTi21-Reed-[RFDM]
Slave Channel | VTi21 Input Channel | Quantity | Description | Typical Range | Units | Suggested AoC |
|---|---|---|---|---|---|---|
1 | 1 | CH 1 Frequency | Simple Frequency Measurement (zero crossings) | 0 to 5000 | Hz | 1 |
2 | 1 | CH 1 Total Current | Total current measured in the reed relay frequency range | 0 to 2 mA | mA | 50 |
3 | 1 | CH 1 - spectrogram / gain | Capture waveform showing the magnitude spectrum of the input signal. Use a "Triggered Capture" to acquire the Spectrogram. note: includes only measured frequencies as reported on the other channels. | |||
4 | CH1 Current at F04 | Current measured in-band at 803.25 Hz | 0 to 2 mA | mA | 0.1 | |
5 | CH1 Current at F16 | Current measured in-band at 702.50 Hz | 0 to 2 mA | mA | 0.1 | |
6 | CH1 Current at F17 | Current measured in-band at 697.50 Hz | 0 to 2 mA | mA | 0.1 | |
7 | CH1 Current at F19 | Current measured in-band at 687.00 Hz | 0 to 2 mA | mA | 0.1 | |
8 | CH1 Current at F20 | Current measured in-band at 682.50 Hz | 0 to 2 mA | mA | 0.1 | |
9 | CH1 Current at F26 | Current measured in-band at 611.75 Hz | 0 to 2 mA | mA | 0.1 | |
10 | CH1 Current at F27 | Current measured in-band at 607.75 Hz | 0 to 2 mA | mA | 0.1 | |
11 | CH1 Current at F36 | Current measured in-band at 505.00 Hz | 0 to 2 mA | mA | 0.1 | |
12 | CH1 Current at F38 | Current measured in-band at 493.50 Hz | 0 to 2 mA | mA | 0.1 | |
13 | CH1 Current at F39 | Current measured in-band at 488.00 Hz | 0 to 2 mA | mA | 0.1 | |
14 | CH1 Current at F47 | Current measured in-band at 419.75 Hz | 0 to 2 mA | mA | 0.1 | |
15 | CH1 Current at F48 | Current measured in-band at 410.25 Hz | 0 to 2 mA | mA | 0.1 | |
16 | CH1 Current at F83 | Current measured in-band at 446.00 Hz | 0 to 2 mA | mA | 0.1 | |
17 | CH1 Current at F84 | Current measured in-band a 533.75 Hz | 0 to 2 mA | mA | 0.1 | |
18 | CH1 Current at F92 | Current measured in-band at 842 Hz | 0 to 2 mA | mA | 0.1 |
VTi21-Reed-[FDM2]
Slave Channel | VTi21 Input Channel | Quantity | Description | Typical Range | Units | Suggested AoC |
|---|---|---|---|---|---|---|
1 | 1 | CH 1 Frequency | Simple Frequency Measurement (zero crossings) | 0 to 5000 | Hz | 1 |
2 | 1 | CH 1 Total Current | Total current measured in the reed relay frequency range | 0 to 5A | mA | 50 |
3 | 1 | CH 1 - spectrogram / gain | Capture waveform showing the magnitude spectrum of the input signal. Use a "Triggered Capture" to acquire the Spectrogram. note: includes only measured frequencies as reported on the other channels. | |||
4 | CH1 current at F20 | Current measured in-band at 682.50 Hz | 0 to 2 mA | mA | 0.1 | |
5 | CH1 current at F21 | Current measured in-band at 678.50 Hz | 0 to 2 mA | mA | 0.1 | |
6 | CH1 current at F22 | Current measured in-band at 674.00 Hz | 0 to 2 mA | mA | 0.1 | |
7 | CH1 current at F23 | Current measured in-band at 667.00 Hz | 0 to 2 mA | mA | 0.1 | |
8 | CH1 current at F24 | Current measured in-band at 622.25 Hz | 0 to 2 mA | mA | 0.1 | |
9 | CH1 current at F25 | Current measured in-band at 616.25 Hz | 0 to 2 mA | mA | 0.1 | |
10 | CH1 current at F26 | Current measured in-band at 611.75 Hz | 0 to 2 mA | mA | 0.1 | |
11 | CH1 current at F27 | Current measured in-band at 607.75 Hz | 0 to 2 mA | mA | 0.1 | |
12 | CH1 current at F28 | Current measured in-band at 598.25 Hz | 0 to 2 mA | mA | 0.1 | |
13 | CH1 current at F29 | Current measured in-band at 587.75 Hz | 0 to 2 mA | mA | 0.1 | |
14 | CH1 current at F30 | Current measured in-band at 574.75 Hz | 0 to 2 mA | mA | 0.1 | |
15 | CH1 current at F33 | Current measured in-band at 519.50 Hz | 0 to 2 mA | mA | 0.1 | |
16 | CH1 current at F34 | Current measured in-band at 514.50 Hz | 0 to 2 mA | mA | 0.1 | |
17 | CH1 current at F35 | Current measured in-band at 510.00 Hz | 0 to 2 mA | mA | 0.1 | |
18 | CH1 current at F36 | Current measured in-band at 505.00 Hz | 0 to 2 mA | mA | 0.1 | |
19 |
| CH1 current at F37 | Current measured in-band at 499.50 Hz | 0 to 2 mA | mA | 0.1 |
20 |
| CH1 current at F38 | Current measured in-band at 493.50 Hz | 0 to 2 mA | mA | 0.1 |
VTi21-Reed-[FDM3]
Slave Channel | VTi21 Input Channel | Quantity | Description | Typical Range | Units | Suggested AoC |
|---|---|---|---|---|---|---|
1 | 1 | CH 1 Frequency | Simple Frequency Measurement (zero crossings) | 0 to 5000 | Hz | 1 |
2 | 1 | CH 1 Total Current | Total current measured in the reed relay frequency range | 0 to 5A | mA | 50 |
3 | 1 | CH 1 - spectrogram / gain | Capture waveform showing the magnitude spectrum of the input signal. Use a "Triggered Capture" to acquire the Spectrogram. note: includes only measured frequencies as reported on the other channels. |
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4 |
| CH1 current at F15 | Current measured in-band at 706.50 Hz | 0 to 2 mA | mA | 0.1 |
5 |
| CH1 current at F18 | Current measured in-band at 692.00 Hz | 0 to 2 mA | mA | 0.1 |
6 |
| CH1 current at F39 | Current measured in-band at 488.50 Hz | 0 to 2 mA | mA | 0.1 |
7 |
| CH1 current at F40 | Current measured in-band at 483.00 Hz | 0 to 2 mA | mA | 0.1 |
8 |
| CH1 current at F41 | Current measured in-band at 478.50 Hz | 0 to 2 mA | mA | 0.1 |
9 |
| CH1 current at F42 | Current measured in-band at 473.50 Hz | 0 to 2 mA | mA | 0.1 |