Lake Shore Model 340 Temperature Controller User’s Manual
Analog, Digital, Alarm & Relay Operation
7-3
7.1.4 Manual Mode Operation of the Analog Outputs
During manual operation, the user can set the voltage of an analog output giving them a controlled voltage
source. In manual mode, all analog output parameters are ignored except the bipolar setting and the users
output setting value.
The setting value is given in percent of full scale. With bipolar on, a setting value of -100 % causes an output
voltage of –10 V, and a setting value of +100 % causes an output voltage of +10 V. With bipolar off (unipolar)
a setting value of 0 % causes an output voltage of 0 V, and a setting value of +100 % causes an output
voltage of +10 V. Negative setting values cause an output voltage of 0 V if bipolar is off.
The resolution of the analog output hardware is 1.25 mV or 0.0125% of full scale. Setting resolution of the
output value is 0.01 %.
To set an analog output voltage, press the
Analog Outputs
key and set the mode to manual and set bipolar
setting as described in Paragraph 7.1. Press the
Next Setting
key until the value field is highlighted. Use the
number keys to enter the desired output, then press the
Enter
key. Press the
Save Screen
key to store the
changes. The default value is 0%.
7.2 DIGITAL INPUTS AND OUTPUTS (I/O)
The Model 340 has six digital inputs and five digital outputs. The digital inputs and outputs can be used to
monitor instrument status in a pre-programmed mode of operation or they can also be used in manual mode
to control and monitor external events. The connector pinout and hardware information about the digital
signals is provided in Paragraph 3.7. The digital signal lines are protected against short circuit and over
voltage but it is not recommended to expose the terminals to ESD or voltages higher than +5 V or lower than
ground provided on the Digital I/O connector.
7.2.1 Digital Output Modes
Model 340 digital outputs have
four modes of operation.
To select a digital output mode,
press the
Options
key. The
DIGITAL I/O
screen appears
with the output mode
highlighted. Use the
s
or
t
key to select the desired mode. Press the
Enter
or
Next Setting
key to advance
to other settings, or press the
Save Screen
key to store changes. The default setting is Off.
7.2.2 Digital Outputs in Alarm Mode
In alarm mode, the digital outputs report the alarm status of the sensor input alarms. The digital output is low,
logic 0, to indicate no alarm condition and high, logic 1, to indicate an alarm condition exists. Alarms for a
given sensor input must be turned on for this feature to operate. The sensor input alarms are mapped to the
digital output signals as follows:
Input Alarm:
Any Other *
B High
B Low
A High
A Low
Digital Output Number:
DO5 DO4 DO3
DO2
DO1
Digital I/O Connector Pin:
5 4 3
2
1
* “Any Other” indicates that an alarm is active on any one of the installed optional inputs.
7.2.3 Digital Outputs in Scanner Mode
Digital outputs can be used to report the scan channel when an external scanner is being used. The digital
outputs must be put in scanner mode as described in Paragraph 7.2.1. External scanner operation is
described in Paragraph 5.4.
OFF
All digital outputs set to zero.
ALARMS
Used to indicate the alarm status of the sensor inputs.
MANUAL
Set by user from the front panel or computer interface.
SCANNER
Used with an external scanner (refer to Paragraph 5.4).