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 certain Reed frequencies / channels.

The set supported depends on which firmware variant is selected. Contact mpec for more information.

RFDM

FDM2

RFDM

FDM2

Channel

Frequency

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

F20
F21
F22
F23
F24
F25
F26
F27
F28
F29
F30
F33
F34
F35
F36
F37
F38

682.50 Hz
678.50 Hz
674.00 Hz
667.00 Hz
622.25 Hz
616.25 Hz
611.75 Hz
607.75 Hz
598.25 Hz
587.75 Hz
574.75 Hz
519.50 Hz
514.50 Hz
510.00 Hz
505.00 Hz
499.50 Hz
493.50 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

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

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