Operator`s manual

21X MICROLOGGER OVERVIEW
OV-2
The 9-pin serial I/O port provides connection to
data storage peripherals, such as the
SM192/716 Storage Module or RC35 Cassette
Recorder, and provides serial communication to
computer or modem devices for data transfer or
remote programming (Section 6). This 9 pin port
does NOT have the same pin configuration as
the 9 pin serial ports currently used on many
personal computers. An SC32A is required to
interface the 21X to a RS232 serial port
(Section 6).
The panel also contains two terminal strips
which are used for sensor inputs, excitation,
control outputs, etc. Figure OV1-2 shows the
21X panel and the associated programming
instructions.
FIGURE OV1-2. 21X Wiring Panel and Associated Programming Instructions
OV1.1 ANALOG INPUTS
The terminals in the upper strip are for analog
inputs. The numbering on the terminals refers to
the differential channels; i.e., the voltage on the
HI input is measured with respect to the voltage
on the LOW input. When making single-ended
measurements either the HI or the LOW channel
may be used independently to measure the
voltage with respect to the 21X ground. Single-
ended channels are numbered sequentially, e.g.
the HI and LOW sides of differential channel 2
are single-ended channels 3 and 4, respectively
(Section 13.2).
The analog input terminal strip has an insulated
cover to reduce temperature gradients across
the input terminals. The cover is required for
accurate thermocouple measurements (Section
13.4).