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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)