GE 90*-30 PLC Series - Module Description; Functional Characteristics

Q-2 Series 90™-30 PLC LONWORKS® Bus Interface Module User's Manual – June 1997 GFK-1322A
Q
Module Description
The Series 90 PLC L
ON
W
ORKS
Bus Interface Module (LBIM) provides an interface between the
GE Series 90-30 PLC and an Echelon L
ON
W
ORKS
network (Figure Q-1). The LBIM can
interface with networks that use twisted pair cabling in bus, loop, or free-topology configurations.
The LBIM can support up to 244 network variables (four of which are reserved as configuration
variables) and map these network variables (NVs) into the %I, %Q, %AI, and %AQ PLC memory
references. The Module adheres to the L
ON
M
ARK
Layers 1-6 Interoperability Guidelines for the
interface to the L
ON
W
ORKS
network.
The LBIM can be located in any rack in any slot (except for the slots in the main rack that are
reserved for the power supply and CPU) in a Series 90-30 PLC. For the most efficient system
operation, the main baseplate is preferred.
The following slots are reserved in the PLC main rack:
Models 331, 340, 341, 351, 352 and later: Slot 0 reserved for power supply
` Slot 1 reserved for CPU
Models 311 and 313: Slot 0 reserved for power supply (The CPU is built into the
baseplate.)
Functional Characteristics
Most parameters are supported to the limits of the L
ON
T
ALK
protocol and those of the L
ON
W
ORKS
node. The module supports up to 240 user NVs. The actual maximum number of NVs depends on
the size and type of the NVs, the PLC available memory space (2kbytes each direction), and the
configuration memory budget. The module supports all Standard Network Variable Types
(SNVTs) as listed in the SNVT Master List published by Echelon Corporation as of June 1996.
Each NV must be no more than 31 Bytes in length. NVs can be mapped into PLC memory types
%I, %Q, %AI, or %AQ. NVs mapped to memory types %I or %Q must be of type
SNVT_lev_disc, SNVT_switch, or other bit-represented types.
When an input NV is updated, the data associated with it are copied into the proper PLC input
buffer location. The Store Inputs routine is then called to update the PLC memory during the next
PLC scan. When the API callback notifies the module that an output scan update has arrived, the
data are copied into a holding buffer. This buffer is then scheduled to be checked against the
current value of each NV output. If the data are different, the NV is updated over the L
ON
W
ORKS
network if the Min Send Time has expired (only if Min Send Time was configured).
The LBIM has four LED indicators that show the module’s operating status. The Service and
Wink functions provided by L
ON
W
ORKS
are implemented in the LBIM (for details, see “Controls
and Indicators”).