User`s manual

www.vtiinstruments.com
EX7000 Series Theory of Operation 51
Additionally, the RDB of the EX7300 and EX7400 may have varying quantities of open-collector
and TTL drive lines, depending on the model ordered. This property is linked to the relay drive
connector banks, as illustrated in Figure 5-2. The following table indicates how banks are used
according the part number assigned.
Part Number
Bank 0
Bank 1
Bank 2
-000
Open-collector
Open-collector
Open-collector
-001
TTL
Open-collector
Open-collector
-002
TTL
TTL
Open-collector
-003
TTL
TTL
TTL
CAUTION
It is imperative that TTL banks only have TTL devices connected to them. Connecting an
open-collector device to a TTL port will result in damage to the RDB and, potentially, to
other equipment in the test system. Failure to comply with this warning will result in voiding
the manufacturer’s warranty.
RELAY ACCESS & CONTROL
Relay Power
Contact
(
1 of 6)
Contact
(2 of 6)
Latch
5V
5V
10k pullup
(optional
)
4
to Comm Bus
to Comm Bus
Indicator Contact
1
(relay dependent)
to Comm Bus
ID Bits
(relay dependent)
Indicator Contact 2
(relay dependent)
Reset Line
Latching Relays
10k pullup
(optional)
RDB
User Connections
F
IGURE 5-3: RELAY DRIVER BLOCK DIAGRAM
When asserted, the relay drive lines will sink the necessary current through the coils, effectively
switching the relay. The user can program the relay settling time for each RDB.
The relay control can be operated in two modes: Pulse and Continuous
Continuous Mode
Connecting non-latching devices to any bank of the RDB will dictate that bank must be operating
in continuous mode. Commanded by software, the latch signal driving the FET will change state
to activate/deactivate FETs and continuously stay in that state until the next command. All Relay
Control Drive bits within a bank will change state at the same time. Continuous mode requires a