Picking a PC Watchdog
We often get calls and emails from people asking us which PC Watchdog board
they should pick or which one is best for a particular application.
We will try to answer the question here.
PCI & PCIe (Express) PC Watchdog
These two boards are essentially the same except for their bus interface.
They are good choices if you need additional I/O capability. They both have a
DB-25 connector on the rear of the board for I/O connectivity.
There are 4 general purpose digital inputs. They could be used for entry or
tamper switch detection in a kiosk type application. There are four general purpose
digital (open-collector) outputs that could be used to trigger external audible
alarms, lights, or alarm panels. These I/O points are controlled and accessed with
the DLL and there is sample code on the CD showing how it is done.
There is a digital (open-collector) high current output that indicates there
is an over-temp condition. Once again this could trigger external audible alarms,
lights, or alarm panels.
There is one more external digital input that can be used as a watchdog “tickle” signal
or it can detect edges on the input. This would be useful for tamper switches.
One input is an analog-to-digital input to sense voltages between 0.0 to +5.0V
and return an eight bit value. It is not a precision input but it would work for
temperature sensors. There is limited +5.0V and Ground on the DB-25 to power a remote sensor.
Lastly there are two DPDT (2 form C) relays with all their dry contacts available.
They can be configured to pulse or latch after a watchdog time out via the DIP Switches.
You can also use the DLL to gain exclusive use of one relay.
USB PC Watchdog
This is the cheapest version of a PC Watchdog we offer for basic watchdog functionality.
It does have some additional I/O.
There is one digital input that can be used as a watchdog “tickle” signal or it can
detect edges on the input. This would be useful for tamper switches.
There is one SPST (1 form A) relay that can be setup with the config program to
generate a pulse or latch on after a watchdog time out. It can also be set to
power up in the ON state as if it were a normally closed type. The relay can also be
controlled with the DLL.
Internal Serial PC Watchdog
This device is version can be used without installing any watchdog software if you
have a current serial device connected to a PC that has frequent data transfers.
You can insert this board in-line with the serial stream and it will monitor the
traffic on the serial link. If the PC locks up and stops sending data the watchdog
will time out and reboot the PC.
It can also be used like any other Watchdog with the Config program and the DLL.
It also has an SPST relay that operates just like the one on the USB version.
External Serial PC Watchdog
This version works like the Internal Serial version. It can monitor serial line traffic
between the PC and an external device and reboot the PC when it locks up and stops send data.
It has the ability (with an option power module) to cycle the AC power on the PC and additional
remote AC powered devices. This is an option for PCs without a motherboard reset header.