Lake Shore Model 340 Temperature Controller User’s Manual
3-12
Installation
3.7 DIGITAL
I/O
The connector labeled Digital I/O on the
rear panel of the Model 340 has terminal
pins with digital inputs and outputs along
with power supplies. See Figure 3-6.
The digital inputs and outputs can be
used to in applications that involve
auxiliary sensor input scanners. These
signals can also be used in manual
mode to control and monitor external
events. The power supplies are
provided for external circuit
applications that require low current.
The digital inputs and outputs are
Transistor-to-Transistor Logic (TTL)
voltage level compatible. They are
protected against short circuit and over
voltage, but it is not recommended to
expose the terminals to electrostatic
discharge (ESD), voltages higher than
5 volts, or lower than ground. Using
more current than the limits in Figure
3-6 is not recommended because the
additional load on instrument power
supplies causes noise on internal
circuits. All signals and power supplies
should be returned to the ground pin
whenever possible. Even though the
ground pin is connected to chassis
ground inside the Model 340, attaching
the ground pin to external grounds can
cause noise on the sensor input measurements.
The connector is a 15 pin D-style socket. This is a common socket (P/N 268-303) and mating plug
(P/N 268-301) can be purchased from Lake Shore or any local electronic supplier.
3.8 RELAYS
The Model 340 has one high and one low relay, shown in
Figure 3-7. They are most commonly associated with the
alarm feature. The relays can also be put in manual
mode and controlled directly by the user from the front
panel or over computer interface. Refer to Paragraph
7.4. The relay status indicated on the relays and beeper
screen is for monitoring the relay status. It can not be set
by the user. If a relay is inactive (Off), it will be in its
normal state of open or closed. When the relay is active
(On), it will be in the opposite state.
The relay outputs have a detachable 6-pin terminal block connector.
The connector can be removed from its socket for convenient
installation of wires. The connector is included with the Model 340
(P/N 106-737). The connector manufacturer indicates that up to 12
AWG stranded copper wire can be used with the connector. It is
unlikely that wire that large will be required to carry the rated 2 amp
current of the relay.
5
4
3
2
1
15
14
13
12
DIGITAL I/O
8
7
6
11
10
9
Pin
Symbol
Description
Type or Limit
1
DO1
Digital Output 1
TTL Output
2
DO2
Digital Output 2
TTL Output
3
DO3
Digital Output 3
TTL Output
4
DO4
Digital Output 4
TTL Output
5
DO5
Digital Output 5
TTL Output
6
Reserved/DI6 Acting as Digital Input 6
TTL Input
7
+5 V
+5 Volts Output
100 mA max
8
+15 V
+5 Volts Output
50 mA max
9
DI1
Digital Input 1
TTL Input
10
DI2
Digital Input 2
TTL Input
11
DI3
Digital Input 3
TTL Input
12
DI4
Digital Input 4
TTL Input
13
DI5
Digital Input 5
TTL Input
14
-15 V
-15 Volt Output
50 mA max
15 Gnd
Ground
-
Figure 3-6. DIGITAL I/O DA-15 Rear Panel Connector Details
Slides into RELAYS slot
in rear of Model 340
Use
screwdriver
to lock or
unlock wires
Insert wire
into slot
1
2
3
4
5
6
Screw Terminal
Connector
Lake Shore
P/N 106-737
PIN DESCRIPTION
1
2
3
4
5
6
Low, Normally Closed (N.C.)
Low, Common
Low, Normally Open (N.O.)
High, Normally Closed (N.C.)
High, Common
High, Normally Open (N.O.)
Figure 3-7 RELAYS LO and HI
Rear Panel Connector Details