Watlow Series 734 Data Communications Manual de usuario descargar pdf (Pagina 11)

WATLOW Series 733/734

How to Use Data Communications

See Syntax

Figure 5 -

Series 733/734

General Message

Syntax Example.

ASCII

Characters

HEX

Value

Space

41 4C31 20 35 30 30

<Space>

3D 20

<CR>

Example Format

For your benefit, we're presenting message/response examples with syntax

required for Series 733/734 communication. Information bracketed by < > indi-

cates a description, rather than literal characters. We show each ASCII character

that you must transmit to the Series 733/734, including space between the charac-

ters. (A "space" is itself an ASCII character, hex 20). For clarity, we also represent

each ASCII character as a hexadecimal pair. The pairs are spread apart on the

page for easy reading. However, electronic devices "see" the hex pairs all together

in "strings," with no spaces in between.

For instance, from the example just below, you want to set the Alarm 1 Low

(A1LO) prompt to 500°. Notice the syntax just below which uses the "=" command.

= <space> A1LO <space> 500

To send this message, key the ASCII characters into your computer, or write them

into your program. The computer, in turn, will send a string similar to the one at the

bottom of the example, 3D2041314C4F20353030.

Notice that we haven't mentioned protocol here, or any characters added to this

syntax by a protocol. With XON/XOFF, the message above can be transmitted

with only an additional Carriage Return <cr> (hex 0D) character at the end. How-

ever, the ANSI X3.28 Protocol requires an envelope of Start of Text <STX> (hex

02) and End of Text <ETX> (hex 03) characters around the information you see

above. You'll learn how to do that in the pages ahead.

XON/XOFF Protocol for EIA/TIA-423

XON/XOFF (flow control) Protocol allows a communicating device (either a 733/

734 or the host) to suspend transmission of all messages from the other device,

and then to continue transmission when it's again ready.

The device that needs to suspend transmission sends the XOFF character

(hex 13) to stop the other device's transmitter, and XON (hex 11) to restart it. Note

that technically any character will restart the transmitter, but only the XON charac-

ter is not a part of any regular message that may be transferring.

Messages transmit according to the syntax described in the XON/XOFF formats

which follow for each command.

The XON/XOFF Protocol requires a Carriage Return <cr> character

(hex 0D) at the end of every message.

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 23 24

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