SETTING JUMPERS
SNAP-LCM4 User’s Guide
13
Setting the Host Port Baud Rate
The factory setting for the host port baud rate is 38.4 KBd, but
baud rates from 300 Bd to 115.2 KBd are selectable using
jumpers B0 through B3. In general, it is best to choose the
fastest baud rate the host computer and the controller will
both support. Lower baud rates may be necessary for long
cable runs, in high-noise environments, or for compatibility
with modems or other data transmission equipment.
The table at right shows jumper settings for available baud
rates. The shaded entry is the default setting.
Setting the Communication Mode
You can select ASCII or binary communication mode using jumper X0.
The factory default is binary, which is generally faster than ASCII. ASCII is
typically used only for compatibility with modems or other data
transmission equipment, or with host devices that for some reason
cannot support binary mode.
Setting the Boot Mode
The boot mode jumpers determine how the controller acts when it is turned on. The AUTO, E/R, and X1
jumpers set the boot mode.
AUTO and E/R Jumpers
The AUTO jumper determines whether the controller automatically starts running your strategy (autoboot) or
waits until instructed to do so by the host computer. The E/R jumper determines whether the strategy is
executed from battery-backed RAM or from Flash ROM. The factory settings are non-autoboot and execute
from RAM.
There is no operational difference between execution from battery-backed RAM or ROM, except that the
SNAP-LCM4 has significantly more space available in RAM for program storage. The drawback to execution
from RAM is that the program is lost when the backup battery dies. (Battery life typically exceeds three years.)
Before the controller will execute a program from ROM, you must have stored the program in Flash ROM by
selecting that download function in OptoControl. In general, it is best to wait until program development is
complete to use the autoboot feature or store the program in Flash ROM.
X1 Jumper
Under normal conditions, you can update the controller firmware with the X1 jumper in the default position
(boot to kernel).
If the firmware in the controller has somehow been corrupted,
however, and the controller cannot execute its full kernel
properly, remove this jumper. Removing the X1 jumper sets the
controller to “boot to loader” mode, preparing it to receive the
firmware download from the loader.
The table at right shows Auto, E/R, and X1 jumper settings.
Default settings are shaded.
Baud Rate
B0
B1
B2
B3
115.2 KBd
Out
In
In
In
76.8 KBd
In
Out
In
In
57.6 KBd
Out
Out
In
In
38.4 KBd
In
In
Out
In
19.2 KBd
Out
In
Out
In
9600 Bd
In
Out
Out
In
4800 Bd
Out
Out
Out
In
2400 Bd
In
In
In
Out
1200 Bd
Out
In
In
Out
600 Bd
In
Out
In
Out
300 Bd
Out
Out
In
Out
Communication Mode
X0
Binary
In
ASCII
Out
Boot Mode
Auto E/R X1
Autoboot enabled
In
Autoboot disabled
Out
Run from RAM
In
Run from EEPROM
Out
Boot to kernel
In
Boot to loader
Out
