Rice Lake Digital/Diagnostic - iQube - Manual (Page 8)

Installation 5
2.5 Serial Communications
The J4 and J7 serial communications ports on the
iQUBE connector board support communications
between the iQUBE and a host device (indicator or
PC) or other iQUBE units.
• Port J7 supports full-duplex RS-232 or
four-wire RS-485 communications between
the primary
iQUBE unit and a host device.
The communications protocol (RS-232 or
RS-485) and port used to communicate with
the host device are selected by setting DIP
switches on the core module (see Section 2.9
on page 10).
NOTE: Four-wire RS-485 communications with
the 920i requires installation of the serial option
card in the indicator. See Table 2-4.
Port J7 is also used by secondary iQUBE units
to connect to the master and secondary unit.
• Port J4 supports full-duplex RS-485
communication between the primary
iQUBE
unit and any secondary iQUBE , and between
successive secondary units (see Section 2.6).
To attach serial communications cables, route the
cable through the cord grip and wire to the connector.
Use cable ties to secure serial cables to the inside of
the enclosure.
Table 2-3 shows the pin assignments for connectors
J4 and J7. See Section 2.6 for information about
wiring for secondary units.
RS-485 Connections to Host 920i
Table 2-4 shows the connections needed for RS-485
communications between a host
920i and the iQUBE .
The 920i serial expansion card, PN 67604, must be
i n s t a l l e d i n t h e i n d i c a t o r f o r 4 - w i r e R S - 4 8 5
communications with the
iQUBE .
NOTE : RS-485 is only supported on Port A of the
2-channel expansion board.
Communications Cable Distance Limitations
The maximum cable lengths that can be used for
various communications types depend on a number of
factors. These include: output impedance of the
transmitter; electrical noise in the environment; cable
capacitance, gauge, termination, and shielding.
Given that these and other factors will affect the
maximum usable cable length, the following distances
c a n b e u s e d a s a g e n e r a l g u i d e f o r
i Q U B E
communications cabling:
RS-232: 50 ft (15 m)
RS-485: 1000 ft (300 m) (Twised pair cable)
Fiber-optic: 500 ft (150 m)
2.6 Primary/Secondary Configuration
Up to three iQUBE junction boxes can be configured
as secondary units controlled by a primary iQUBE
u n i t . F i g u r e 2 - 4 o n p a g e 7 s h o w s t h e
primary-to-secondary wiring for multiple
iQUBE
units. Successive secondary units are wired in parallel
(A to A, B to B, and so on) as shown in Figure 2-5.
NOTES:
• 120
Ω termination resistors (included in parts
kit) must be installed across the A and B
terminals on the J4 connector of the primary
unit and between the A and B terminals on the
J7 connector of the last secondary unit (see
Figure 2-4 on page 7).
• All six wires, including shield and ground
w i r e s , m u s t b e c o n n e c t e d b e t w e e n t h e
communicating
iQUBE units.
Connector Pin Signal
J7 1 SHIELD
2 GND
3 Z / RS-232 TxD
4 Y
5 B
6 A / RS-232 RxD
J4
1 A (RS-485 +RxD)
2 B (RS-485 –RxD)
3 Y (RS-485 +TxD)
4 Z (RS-485 –TxD)
5 GND
6 SHIELD
Table 2-3. Serial Port Pin Assignments
920i Serial Option Board
J2 Connector
iQUBE
J7 Connector
RS-485 Signal Pin Pin RS-485 Signal
+RxD 1 4 +TxD (Y)
–RxD 2 3 –TxD (Z)
–TxD 3 5 –RxD (B)
+TxD 4 6 +RxD (A)
Table 2-4. RS-485 Connections for 920i Host