Rockwell-automation 5370 Color CVIM Communications Manual Manual de usuario descargar pdf (Pagina 105)

Chapter 5

Using the RS–232 Ports

5–37

To transmit the data value 10 hex, you must use the data code DLE DLE.

However, only one of these DLE data bytes is included in the BCC sum. For

example, to transmit the values 8, 9, 6, 0, 10, 4, and 3 hex, you would use the

following message codes:

Represents single

data byte value of 10

10 02 08 09 06 00 10 10 04 03 10 03 D2

DLE STX Data DLE ETX BCC

In this case, the sum of the data bytes is 2E hex because only one DLE text

code is included in the BCC. So the BCC is D2 hex.

The BCC algorithm provides a medium level of data security. It cannot

detect transposition of bytes during transmission of a packet. It also cannot

detect the insertion or deletion of data values of zero within a packet.

Use the deactivate force command to return outputs on the 2801–JMB local

I/O board to the Color CVIM module assigned functions. The deactivate

forces command is:

If the BCC is not valid, the Color CVIM module will respond with a DLE

NAK and the command will not be executed.

If the BCC is valid, the Color CVIM module will respond with a DLE ACK.

Then the Color CVIM module will validate the command structure. If the

command is valid, the Color CVIM module will execute the command and

return the data. If the command structure is invalid, the Color CVIM module

will not execute the command or respond.

Block Check Character

(cont’d)

Deactivate Forces

1 2 ... 100 101 102 103 104 105 106 107 108 109 110 ... 221 222

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Rockwell-automation 5370 Color CVIM Communications Manual Manual de usuario Pagina 105