Meinberg FDM511 User Manual

Technical Information

Operating Instructions

FDM511

Impressum

Meinberg Funkuhren GmbH & Co. KG
Lange Wand 9
D-31812 Bad Pyrmont

Phone: [phone] / 9309-0
Fax: [phone] / 9309-30

Internet: http://www.meinberg.de
Email: [e-mail]

May 29, 2009

Table of Contents

Impressum ............................................................................................ 2

Features of the Frequency Deviation Monitor FDM511 ....................... 5

Functional Principle..................................................................... 5

The Front Panel Layout............................................................... 6

LED PL Time .................................................................... 6

LED REF Time ................................................................. 6

LED Fail ............................................................................ 6

LED Overflow................................................................... 6

Push Buttons ...................................................................... 6

Display............................................................................... 6

Analog Outputs ........................................................................... 7

Serial COM Ports ........................................................................ 7

EEPROM .................................................................................... 7

Installation ............................................................................................ 7

Power Supply .............................................................................. 7

Input Signals................................................................................ 7

Powering Up the System ............................................................. 8

The Menus in Detail ............................................................................. 8

Menu Frequency ......................................................................... 8

Menu Frequency Deviation ......................................................... 9

Menu REF Time ......................................................................... 9

Menu PL Time ............................................................................ 9

Menu Time Deviation ................................................................. 9

Menu SETUP............................................................................ 10

Menu Nominal Frequency......................................................... 10

Menu Time Deviation Init ......................................................... 11

Menu COM Parameter .............................................................. 11

Menu Output String................................................................... 12

Menu Analog Outputs ............................................................... 12

Menu Error Bits......................................................................... 13

Menu Serial Number ................................................................. 13

Serial Output Strings ........................................................................... 14

Standard FDM String ................................................................ 14

Short FDM String...................................................................... 15

Time Deviation Preset String..................................................... 15

Areva FDM String .................................................................... 16

Over Range Condition .............................................................. 16

Time Deviation Preset ............................................................... 17

Firmware Updates .............................................................................. 18

CE Label ............................................................................................ 18

Technical Specifications FDM511 ..................................................... 20

Time Strings .............................................................................. 21

Format of the Meinberg Standard Time String................. 21

Format of the Uni Erlangen Time String.......................... 22

Rear Connector Pin Descriptions .............................................. 24

Rear Connector Pin Descriptions .............................................. 25

Features of the Frequency Deviation Monitor FDM511

The module FDM511 was designed to calculate and monitor the frequency in 50/60Hz
power line networks. A preconnected reference is necessary that provides a high
accuracy 10MHz clock, a serial time string and a PPS (pulse per second). In addition to
the frequency, the time is calculated that would be displayed by a clock using the mains
frequency as its timekeeping reference (PLT = Power Line Time). The accumulated
differece between the drifting power line time PLT and the high accuracy reference time
REF is called the time deviation (TD). Because the time deviation has the long-term
accuracy of the reference, it is suitable to supervise the frequency stability. The time
deviation can be read out either via serial interface or via one of the two integrated analog
outputs for further evaluation or regulation.

Functional Principle

The power line frequency to be monitored is applied via the rear VG edge connector
(optional: via a mains socket in the frontpanel) of the FDM511, then filtered and
transformed. After that the sine-wave signal is converted into a TTL signal using a
schmitt trigger. The rising edge of this TTL signal is used to start/stop a counter that is
clocked by the high accuracy 10MHz pulse of the reference. Due to this, the period
length of the mains frequency is measured with a resolution of 100ns and read out by the
micro controller of the FDM511. The values are averaged over a period of one second
and then the frequency is calculated with a resolution of 1mHz.

Calculation of the power line time PLT occurs by counting the periods of the mains
frequency. Depending on the nominal frequency, the PLT seconds are incremented after
counting 50 or 60 periods. To initialize the PLT, it is necessary to get the exact time via
the serial interface (REF) and the pulse per second (PPS) from the preconnected
reference. The time deviation TD is calculated once per second and is limited to ±100
seconds.

5

The Front Panel Layout

The 61mm wide front panel contains four LED indicators, two push buttons and a 8-digit
alphanumerical LED display.

LED PL Time

This LED toggles once per second when the mains
frequency is detected correctly. It stops toggling as
soon as the mains frequency fails.

LED REF Time

This LED toggles once per second corresponding to
the pulse per second of the reference. It stops togg­ling as soon as the PPS is not applied any longer.

LED Fail

This LED is switched on whenever a correct
operation of the module is not ensured and the
results are useless. Loss of the PPS, the mains
frequency or the serial time string can cause this.
The reason for the fault can be found out by reading
the Error-Bits.

LED Overflow

This LED is switched on whenever one of the measurements exceeds its limits:

- Time Deviation is more than ±100 seconds

- Frequency is below 45Hz or above 65Hz

- Analog Output exceeds ±2,5V

The LED is switched off again as soon as all values are back within their limits.

Push Buttons

Measurement and status information can be selected to be shown on the display using the
two push buttons. The Menu button is used to skip to several sub menus while the Set
button is used to select the corresponding item and display its content. In the setup menu
the push buttons are also used to change the configuration of the FDM511 or to enter
parameters.

Display

The 8-digit alphanumerical LED display shows the measurements of the FDM511 like
frequency and time deviation. Furthermore, in the setup menu the display is used to show
configuration parameters and status information.

6

Analog Outputs

FDM511 provides two analog outputs for longtime-recording. These outputs have a
range of -2.5V ... +2.5V, divided in 65536 steps. Either the frequency deviation or the
time deviation can be selected for monitoring via one of these analog outputs.

Serial COM Ports

The frequency deviation monitor provides two serial RS-232 interfaces, COM0 and
COM1. Both ports are able to spread the calculated measurements of the FDM511 once
per second, the format of the string can be selected. In addition, COM0 is used for some
serial commands sent to the module, e.g. for setting a time deviation preset value.
Firmware updates are also possible using this port. The serial input of COM1 is used to
read in the time information of the preconnected reference.

EEPROM

The non-volatile EEPROM is used to store the settings of the FDM511. This ensures a
proper restart without any new configuration after the module was switched off for a
certain time. The two push bottons in the front panel and the LED display are used to set
the parameters (see "Menu SETUP").

Installation

Power Supply

FDM511 needs a single supply voltage of +5V/150mA. As soon as the power supply
and the requested input signals are applied, the module starts operation.

Input Signals

The following input signals, provided by a preconnected reference, are necessary for
operation of the frequency deviation monitor FDM511:

a) 10MHz oscillator clock, TTL level, rear edge connector pin Z12
b) pulse per second, TTL level (active-high), rear edge connector pin D6
c) time string, RS-232, rear edge connector pin B10 (RxD1)

A GPS receiver GPS170 or a DCF77 radio clock PZF511 can be used as a reference, for
example.

7

Powering Up the System

If all the input signals, the power supply and the power line to be monitored have been
connected to the FDM511, the system is ready to operate. The "Fail"-LED as well as the
"Overflow"-LED are switched on after power up reset. FDM511 waits for the incoming
serial time string via COM1 to initialize the internal system time (REF time). When this is
done, the PL time is also initialized with the REF time and consequently, the time
deviation TD is set to +00.000s. From now on the REF time is incremented with the PPS
applied while the PL time is incremented by a certain number of recorded mains
frequency periods (50 or 60). The "PL" and "REF"-LEDs start toggling once per
second, corresponding to their time base. The Fail LED is switched off.

The Menus in Detail

After power-up, the type of the module and the firmware revision is displayed for a short
time. Successively, the following items appear before the display begins to shows the
mains frequency automatically:

Knowledge of the firmware revision is helpful whenever technical support from
Meinberg is needed. The Menu button is used to skip to the menus described in the
following. The corresponding content of the menu is displayed after selection is done
with the Set button.

Menu Frequency

The actual calculated mains frequency is displayed with a resolution of 0.001Hz. This is
the default content of the display after powering-up the module.

8