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ROC800-Series Instruction Manual
4-22
Input/Output Modules
Revised Jul-14
The MVS I/O module consists of interface electronics that provide the
communications link between the ROC800 and the MVS devices. The
interface electronics controls communications with the sensor module,
provides scaling of process variables, aids calibration, stores operating
parameters, performs protocol conversion, and responds to requests
from the ROC800.
The ROC800 supports up to two MVS I/O modules. Each MVS I/O
module provides the communications interface and the isolated, short-
circuit current-limited power required to connect up to six MVS sensors.
Note
:
The ROC800 supports up to two MVS I/O modules, or two
MVS modules, or an MVS I/O module and an MVS module.
The MVS I/O module automatically creates six points, one for each of
the six possible MVS channels: 1 – 6 (for one MVS I/O) and 7 – 12 (for
a second MVS module). The system assigns points based on which
module is in the first slot. For example, if an MVS module is in slot 3,
the system automatically assigns it points 1 – 6. If you then install a
second MVS module into slot 1, the system re-assigns points so that slot
1 now holds points 1 – 6 and slot 3 holds points 7 – 12.
The ROC800 allows six MVS devices to be connected on its
communications bus in a multi-drop connection scheme. You must set
the address of each MVS device
prior
to final wiring of multiple MVS
devices. For proper operation of multiple MVS devices, each MVS
device must have a unique address.
None
of the addresses can be 240.
For details on MVS configuration, refer to the
ROCLINK 800
Configuration Software User Manual (for ROC800-Series)
(Part
Number D301250X012) or
ROCLINK 800 Configuration Software User
Manual (for ROC800L)
(Part Number D301246X012).
Once you set a unique address for each MVS, connect the MVS units in
a multi-drop arrangement. The only requirement for wiring multi-drop
devices is that you tie all like terminals together. This means all the “A”
terminals on the devices are electrically connected to the ROC800’s “A”
terminal and so on. Wire each remote MVS transmitter in parallel
(“daisy-chaining”), as shown in
Figure 4-27.
A
B
1000+ meters
(4000+ feet)
120 Ohm
resistor at
end of line
MVS I/O
Module
MVS
transmitter
(up to 6 per
module)
Figure 4-27. MVS Wiring (with Terminators)