Reed FDM Applications

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 the following frequencies:

Channel	Frequency
F04 F16 F17 F19 F20 F26 F27 F36 F38 F39 F47 F48 F83 F84 F92	803.25 Hz 702.50 Hz 697.50 Hz 687.00 Hz 682.50 Hz 611.75 Hz 607.75 Hz 505.00 Hz 493.50 Hz 488.00 Hz 419.75 Hz 410.25 Hz 446.00 Hz 533.75 Hz 842.00 Hz

The VTi21 implements fifteen 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

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 F04	Current measured in-band at 803.25 Hz	0 to 5A	mA	50
5		CH1 Current at F16	Current measured in-band at 702.50 Hz	0 to 5A	mA	50
6		CH1 Current at F17	Current measured in-band at 697.50 Hz	0 to 5A	mA	50
7		CH1 Current at F19	Current measured in-band at 687.00 Hz	0 to 5A	mA	50
8		CH1 Current at F20	Current measured in-band at 682.50 Hz	0 to 5A	mA	50
9		CH1 Current at F26	Current measured in-band at 611.75 Hz	0 to 5A	mA	50
10		CH1 Current at F27	Current measured in-band at 607.75 Hz	0 to 5A	mA	50
11		CH1 Current at F36	Current measured in-band at 505.00 Hz	0 to 5A	mA	50
12		CH1 Current at F38	Current measured in-band at 493.50 Hz	0 to 5A	mA	50
13		CH1 Current at F39	Current measured in-band at 488.00 Hz	0 to 5A	mA	50
14		CH1 Current at F47	Current measured in-band at 419.75 Hz	0 to 5A	mA	50
15		CH1 Current at F48	Current measured in-band at 410.25 Hz	0 to 5A	mA	50
16		CH1 Current at F83	Current measured in-band at 446.00 Hz	0 to 5A	mA	50
17		CH1 Current at F84	Current measured in-band a 533.75 Hz	0 to 5A	mA	50
18		CH1 Current at F92	Current measured in-band at 842 Hz	0 to 5A	mA	50