2-27
2
The first 15 data lines (CH1-15) are sampled at a 1 kHz rate and are inputted
to the Questionable Register. Any changes in the 15 data lines can set bits
in the Questionable Event Register and be used to generate an SRQ or
service request message. The user can select bit transition directions on a
bit-by-bit basis and enable individual bits. The unit's built-in monitoring
function can be used to reduce the bus traffic and the programming load in
the computer. See section 3.4 for directions on programming the Status
Reporting Structure. To take advantage of this capability, it is suggested
that the first one or two bytes be used for signal inputs.
At power turn-on time, the Digital I/O lines are tristated and pulled up to Vcc
by 33 Kohm pullups. The Digital I/O lines are restored to their configured
state 350 ms after power turn-on. Use low true outputs if the device being
driven cannot tolerate a 350 ms delay.
2.10.2 Relay Driver Outputs
There are six low true open-collector relay driver outputs that can be used
to activate relays, solenoids or any device by pulling the load to ground.
Maximum load current for any line is 300 mA.
Figure 2-11 shows the correct output driver signal connections. Connect the
power supply positive terminal to the Driver Voltage Input on pin 8 and to
the plus side of the relay coil or load. Connect the minus side of the coil or
load to a driver output. Connect the Driver Return line on Pin 9 to the power
supply minus terminal. Place a transient suppression diode across any
inductive load to suppress turnoff transients.
Relay
Power
Supply
+
-
Dvr Voltage In
Dvr Return
4807/2307
External Relay Connections
Dvr Out
Diode
Relay
Coil
8
9
31-49
+
-
Figure 2-11 Output Driver Connections
