Nexus 21 A1557 - Manual (Page 9)

Document Ref: Nex8inst.doc/Rev0 09.07.00 Page 9 of 30 Originator MC Checked by AC__
3.0 Engineer’s Functions
A number of engineering functions are provided by the control unit in order to allow the system
to be configured specifically to accommodate site requirements. Further functions are provided
to assist in commissioning and servicing the finished fire detection system.
There are three separate codes for access to the three engineer function levels. When the codes
have been entered, the user is guided through the sequence of operations, for the chosen
function, by text displayed on the LCD.
Prior to entering the engineers function menus, it is necessary to check that the panel is
configured to the correct quantity of loops, open the display door and locate the 4 position DIL
switch marked SW1. The switch settings are tabulated below:
SW1-3 SW1-2 SW1-1 NUMBER LOOPS
OFF OFF OFF 1 LOOP
OFF OFF ON 2 LOOP
OFF ON OFF 3 LOOP
OFF ON ON 4 LOOP
ON OFF OFF 5 LOOP
ON OFF ON 6 LOOP
ON ON OFF 7 LOOP
ON ON ON 8 LOOP
SW1-4 should be in the OFF position if the panel is to operate as a standard system. If the panel
is to operate as part of a network system then SW1-4 should be in the ON position.
Notes: The time/date function is now backed up by an internal lithium “coin cell”. This
battery is non rechargeable but at 70 mAh, will support the clock in conditions of total power
failure, for 10 years. The replacement of this battery is intended to be carried out by service
engineers only. The part number is CR1620.
The download lead is a standard “null-modem” RS232 lead with 9 pin D type connectors. This
can be supplied by CEL or obtained direct from Maplins - catalogue ref VD76H. New lead
connections below:
Panel end PC end
Pin Link Pin Link
2 3
3 2
7 8
8 7
5 5
1 4
6
4 1
6
9 9
The “Cherry” keyboard in current use can be connected directly to the motherboard via J14 5
pin Din socket without use of the converter lead.