WebControl
TM
PLC User Guide Version 3.02.17f
Copyright(c) 2008,-2013 CAI Networks, Inc. 21
5 Real Time Clock
WebControl
TM
has a build-in clock functions that doing time keeping by using an
atomic clock via the simple network timer protocol (SNTP). Configuration is required
to set the correct time zone of the clock. When NTP is not available, WebControl
TM
will use its own crystal to maintain the clock accuracy. If NTP is available, only need
to set the time zone in the clock page. If NTP is not available, please set your local
clock in the clock page also. Without NTP, its internal clock may not as accurate.
Firmware 3.2.9 and later supports DS2417 real time clock IC. Please reference to
Maxim-IC web site for DS2417 and its PCB layout recommendation. To build an
accurate real time clock, the crystal with exactly the part number listed in the Maxim-
IC document is critical.
WebControl will check if a DS2417 existence during power up. Once it finds the
DS2417, it will get its clock synced with DS2417 every 10 minutes. User can update
the clock in DS2417 by manually go to “General Setup” screen, put the date and time
in that field. The DS2417 will get its clock synced up from that. Or, if NTP is working,
WebControl will update DS2417 internal clock every 10 minutes.
5.1 Network Requirements to Use the NTP
WebControl
TM
must be connected to a network that has access to a DNS server. The
primary and secondary DNS server addresses of WebControl
TM
are required to be
configured correctly. WebControl
TM
will use DNS to resolve the name of the
timeserver. The NTP server WebControl accessing is pool.ntp.org. If internal NTP
server must be used, DNS server must resolve the name record for pool.ntp.org to
your local NTP server’s IP address.
5.2 Realtime Clock Use DS2417
WebControl
TM
with firmware 3.2.9 supports DS2417 real-time clock. DS2417 takes
one 32.768 kHz crystal, EPSON part number C-002RX or C-004R (make sure load
capacitance is 6pF). One can easily solder the parts similar to this PCB layout:
Figure 11.0 DS2417 layout
