Meinberg FDM509 User Manual

Technical Information

Operating Instructions

FDM509

Impressum

Meinberg Funkuhren GmbH & Co. KG
Auf der Landwehr 22
D-31812 Bad Pyrmont

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

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

March 8, 2006

Table of Contents

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

Generally .............................................................................................. 5

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

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

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

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

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

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

Push Button Reset ....................................................................... 6

Mains Socket Power Line (optional) .......................................... 7

Installation FDM509 ............................................................................ 7

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

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

Powering Up the System ............................................................ 7

Configuration ....................................................................................... 8

Power Line Frequency ................................................................ 8

Average and Serial Output String .............................................. 8

Initialize Power Line Time ......................................................... 8

Output String .............................................................................. 9

The serial RS232 ports ............................................................. 10

Analog Output .......................................................................... 10

Serial Reset Command ....................................................................... 10

Error Bits ............................................................................................ 11

Analog Values .................................................................................... 11

Firmware Updates .............................................................................. 12

Inquiring Serial Number and Software Revision ............................... 12

CE Label ............................................................................................ 12

Technical Specifications FDM509..................................................... 14

Format of the Meinberg Standard Time String ........................ 15

Rear Connector Pin Descriptions ............................................. 16

Rear Connector Pin Descriptions ............................................. 17

Component Layout ................................................................... 19

Generally

The module FDM509 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 frequency, a serial time string and a PPS (pulse per second).
Additional to the frequency the "PLT" (Power Line Time) is calculated that would be
displayed by a clock using the mains frequency as its timekeeping reference. The
accumulated differece between the drifting power line time and the high accuracy
reference time (REF) is called "time deviation". 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 the 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 FDM509, then filtered and
transformed. After that the sine-wave signal is converted into a TTL signal using a
schmitt trigger. The rising edge of the TTL signal is used to start/stop a counter that is
clocked by the high accuracy 10MHz pulse of the reference. Because of that the period
length of the mains frequency is measured with a resolution of 100ns and read out by
the micro controller of the FDM509. The values are averaged over a period of one
second or one minute (selectable) and then the frequency is calculated with a resoluti­on of 1mHz.

Calculation of the PL time occurs by counting the periods of the power line
frequency. Depending on the nominal frequency the PL time seconds are incremented
after counting 50 or 60 periods. To initialize the PL time it is necessary to get the exact
time via the serial interface. The time deviation is calculated once per second or once
per minute and is limited to ±100 seconds.

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The Front Panel Layout

The 40.6mm wide front panel integrates four LED
indicators and a covered push button.

LED PL Time

This LED toggles once per second corresponding to
the power line time seconds when the mains frequen­cy is detected correctly. It stops toggling if either the
mains frequency or the 10MHz reference is not app­lied or the REF time could not be read out after reset.

LED REF Time

This LED toggles once per second corresponding to
the pulse per second of the reference. It stops togg­ling if either the PPS or the 10MHz reference is not
applied or the REF time could not be read out after
reset.

LED Overflow

This LED is switched on when the time deviation
(the difference between REF time and PL time) ex­ceeds the limit of ±100 seconds. It is switched off
again when either the time deviation is dropped be­low ±100 seconds or a reset sets the time deviation
back to zero.

LED Fail

This LED is switched on if correct operation of the module is not ensured and the
results are unusable. Loosing the PPS or the 10MHz from the referenc could be a
reason for this as well as an error in reading in the REF time. The serial output of the
measure string is stopped when this LED is switched on.

Push Button Reset

The time deviation is set to zero if this covered key is pressed for one second at least.
Furthermore the PL time is initialized with the REF time, provided that a time string is
applied to the serial port COM1 and the corresponding DIP switch is set. If not, both
the PL time and the REF time are set to 00:00:00. Also all error bits are cleared and the
analog outputs are set to their initial state (0V). Pressing the reset key has the same
effect than causing a hardware power-up reset or sending a serial reset command.

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