18
Publication S130E
Issue 1.0
Pakscan IIS Technical Manual
J2, J3 - EPROM Memory Size Select
The usual size is 27c2001 though other devices may be
fitted. These settings do not require adjustment after
leaving the factory.
J4 - RAM Select
The standard unit has a 1 Meg RAM chip fitted.
J5, J6 and J10, LK6 - Comms Port 1
These select the mode for Port 1 communications, either
RS232 or RS485. In addition if, when in RS232 mode,
there is a need for modem control lines the signals to
these can be enabled or disabled. The modem control line links (J6 and J10) should not be fitted if the port is
in RS485 mode. The default setting is for the port to be set for RS232 with modem control enabled.
J7, J8 and J9, LK7 - Comms Port 2
These select the mode for Port 2 communications, either
RS232 or RS485. In addition if, when in RS232 mode,
there is a need for modem control lines the signals to
these can be enabled or disabled. The modem control line links (J7 and J9) should not be fitted if the port is in
RS485 mode. The default setting is for the port to be set for RS232 with modem control enabled.
J11 - Memory backup capacitor discharge
This link provides the facility to completely discharge the RAM power supply capacitor. The RAM data is
supported by a large capacitor that is effective for several minutes in keeping the chip data valid whilst the
main battery is changed. If the contents of the RAM are to be eliminated and the system returned to its default
values then the battery can be removed and this link fitted to discharge the power source. Discharging
completely will take several hours.
The link is normally not fitted. Great care must be exercised if the link is to be fitted.
J12 - Disable automatic watchdog reset
When fitted this link disables the watchdog circuit from resetting the processor. It is not normally fitted as in
most cases it is desirable to restart the processor on a watchdog failure.
Jumper / Link .
Function
Default
Action
LK3
Not used
LK4
Screen A to earth select
yes
link screen ‘A’ to earth
LK5
Screen B to earth select
no
screen ‘B’ not connected
LK6
Port 1 mode select
yes
select RS232
LK7
Port 2 mode select
yes
select RS232
EPROM Type
J2
J3
27c512
no
B position
27c1001
B position
no
27c2001
B position
A position
27c4001
A position
A position
RAM Type
J4
1 Meg
B position
4 Meg
A position
Port 1
LK6
J5
J6 (RTS)
J10 (CTS)
RS232
yes
A
A
A
RS485
no
B
no
no
Port 2
LK7
J8
J9 (RTS)
J7 (CTS)
RS232
yes
A
A
A
RS485
no
B
no
no
