[time-nuts] Used ESE ES-911/GPS/NTP Master Time Clock

[Mark Sims]

I got my ESE ES-911 to work.    The problem that I was seeing was that the unit was not seeing data from the GPS receiver... it would not show a GPS lock, even though the GPS receiver (a Motorola M12+) was working properly.    Probing around the ESE motherboard showed the GPS receiver was not sending any data.    I assumed (improperly) that the GPS receiver was not being initialized to send data by one of the two microprocessors on the ESE motherboard (no data seen being sent to the GPS receiver).

There are two batteries in the ES-911.  One is a 6V 1.2Ah gel cell.   The other is a tiny ML-621 rechargeable lithium coin cell on the back of the GPS board.   Both batteries were dead.   It turns out that the microprocessors do NOT initialize the GPS receiver!   You have to do that over the "auxiliary" data port (the DB-25 connector).  Pin 2 is the "config" pin.  It is a RS-232 level serial input connected to the GPS receiver RXD input pin.  There is no external connection to the GPS TXD signal so you cannot monitor the GPS receiver.

To initialize the GPS receiver, I built a two wire adapter cable to connect a PC serial port to the ESE "aux" connector (PC pin 3 (TXD) to ESE pin 2,  ESE pin 7 (ground) to PC pin 5.  I then used Lady Heather configured to talk to Motorola receivers (heather /rxm /serial_port#)  This sends commands to initialize the Motorola receiver on the ES-911 motherboard.  Voila... ESE-911 started working properly.  Note that Heather will complain about not seeing any data from the receiver since the ES-911 does not have any way to send the GPS serial data to the outside world.

While connected to the "config" port you can use the "PC" keyboard command to set the antenna cable delay.  Note that this will be a "blind" command with no apparent response back to the computer.

After initializing the GPS receiver I moved the PC serial port cable to the ES-911 "broadcast" connector and re-started Heather.  Heather v6.30 and later can decode the ES-911 time codes sent out the "broadcast" port.

So if your ESE ES-911 loses input power,  6V backup battery power, and the GPS coin cell drains then you will need to fix the battery problems and then manually re-initialize the GPS receiver in order to get the device working again!