Air Products Gasguard 250, Руководство по установке

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Section 4: Electrical Connections
Revision D: June 1997 Page 4 - 13
4.5.6 MMMS Network Interface Box
The MMMS Network Interface Box consists of a rack enclosure which contains a
RS232 communications processor and a bank of RS-485 converter boards. The
cabling which connects to the cabinet and VMB controllers is terminated to the
rear of the RS-485 converter rack via screw terminals. Each of the 16 ports is
provided with a set of screw terminals. The RS232 communications processor has
a single 10BASE-T Ethernet connection and an AUI type Ethernet connection on
its rear apron. This Ethernet connection is used for connecting the
communications processor to the MMMS VAX station. The provided AUI port
can be used in installations where the Ethernet connection available is other than
10BASE-T, and accepts a variety of standard Ethernet converter modules.
The MMMS Network Interface Box was designed to allow front and back access
to the rack mounted components, even if the assembly was wall mounted. To
accomplish this, the box is double hinged, and contains conduit penetration areas
on the top and bottom of the rear stationary section. This conduit area is used for
the connections to the RS-485 signal wires (to the cabinets), Ethernet, and for
power connections.
The MMMS Network Interface Box was designed with additional space to allow
for the field installation of an additional communications processor and an addition
bank of RS-485 converter boards to expand the number of available ports from 16
to 32.
4.5.7 MMMS Network Field Wiring
Figure 4.12 shows the MMMS network field wiring between GG250 cabinets/
VMBs and the GG250 Interface Box. Figure 4.13 shows the field wiring between
Span LR300 displays and the GG250 Interface Box. Cable specifications follow:
Recommended cable - Belden specification 9842
Acceptable alternates - Belden specifications 8132, 8102 or 8162