SSR-1U User’s Manual
Rev -, 27 Dec 2019
© 2019 Slerj, LLC
11
www.slerj.com
3
Functional Overview
The SSR-1U consists of four asynchronous serial channels, a data recording subsystem, a user
interface module, a real-time clock, digital input/output for status and control, and a USB
interface for accessing microSD card data as a mass storage device.
3.1
Serial Channels
The behavior of each serial channel is independent and is defined by a number of configurable
parameters, which can be changed using the interactive shell or the control protocol, documented
in Sections 4 and 5, respectively. Those parameters are:
Baud rate – 600 to 230400 baud, inclusive
Bits – 8 or 7
Parity – Even, odd, or none
Stop – 1, 1.5 or 2 stop bits.
Echo – (Boolean) Echoes received characters out through the transmitter.
Function
o
disabled
– The channel is not used.
o
record
– The channel will record received data when commanded.
o
shell
– The channel will be tied to the interactive user shell function of the user
interface module.
o
control
– The channel will be tied to the control protocol function of the user
interface module.
Note that the user interface module can be attached only to a single channel. If
one of the channels is assigned to either the SHELL or CONTROL functions, no
other channel may be assigned to SHELL or CONTROL.
3.2
Record Function
In addition to the basic serial channel parameters above, when a channel is assigned to the
RECORD function, several other configurable parameters apply:
Command Source
Command Source
determines how the channel is commanded to record. Options include
a discrete digital signal, a PWM signal, or software controlled through the user interface
module (shell or control protocol).
Command Source
for a channel can be set to one of
the following:
o
-soft
– The channel records when the
Soft Command
parameter (defined in the
next major bullet) is
true.
With -soft,
Soft Command
is set to
false
at startup, and
the DI and PI pins are ignored.