Remote-processing RPC-330 Manuel d'utilisateur télécharger pdf (Page 14)

SERIAL PORTS SECTION 4

Page 4-1 RPC-330

Figure 4-1 Serial port and jumper locations

DESCRIPTION

The RPC -330 has two serial ports that interface to a

printer, terminal, RS-485 network, or other serial

devices. This section describes their characteristics and

how to use them. Frequent references are m ade to

commands listed in the BASIC-52 Programm ing Manual

or RPBASIC-52 Software Supplement in this manua l.

Please refer to these manuals for more information about

these commands.

Serial por ts are num bered C OM 0 and CO M1. COM 0 is

RS232 only and is used for progr am development.

During r un time, it can be used for other functions.

COM 1 is a general purpose port and is jumperable for

RS-232 or RS-422/485.

Each port has a 256 character interrupt driven input and

output buffer. This allows characters to be sent out

(using PRINT) without slowing down program

execution. However, if the PRINT buffer fills, program

execution is suspended until all PRINT charac ters ar e in

the buffer. Both ports have a 256 character input buffer.

When more than 256 char acters are r eceived, excess

ones are ignored.

CONFIG BAUD controls baud rate and RS-232/485

mode (COM1 only).

ON C OM$ is useful whe n data is sent in pac kets. This

multitasking command branches to a BASIC subroutine

when a specific character or number of chara cters is

received.

Another useful function is STR. Strings can be

formatted, analyzed for length and content. When used

in conjunction with ON COM$, networ king over RS-485

is much easier than with the original BASIC-52.

COM0 SERIAL PORT

This port uses a VTC-9F serial cable to connect external

serial devices to the port. The cable con sists of a 10 pin

IDC connector wired one-to-one to a DB-9 connector.

Line 10 is sim ply cut off. The pin out is designed so it

plugs directly into the 9 pin serial port connector on a

PC.

CTS is a output and is set to high on power up.

Normally, this tells the other device to send data. The

CTS line may be set high or low to hold off

communication. The sending device must have a RTS

input. Line 400 sets CTS high and 500 sets it low, or to

hold off.

400 LINEB 5,0,(LINEB(5,0) .AND. 247)

500 LINEB 5,0,(LINEB(5,0) .OR. 8)

The RTS line is read using the following example:

100 B = LINEB(5,1) .AND. 8

COM 0 is normally used for program ming. D uring run

time it may be used as a general purpose serial por t.

When used for programming or with the INPUT

statement, it will accept ASCII character values from 0

to 127. When used with the GET function, it will return

ASCII values from 0 to 255.

COM1 SERIAL PORT

COM 1 is either an RS-232 or RS-422/ 485 port. A

VTC-9F serial cable, described above, is used for RS-

232 level communications. RS-485 is from screw

terminals. COM 1 has 2 hardw are handshaking lines,

CTS and RTS.

RTS is an input to the card. W hen RT S to the car d is

low, it usually indicates the sender does not want any

data sent to it. The status of this port is read by the

LINEB statement. The example below returns a status

of the RTS line:

100 B = LINEB(5,1) .AND. 32

If B = 32, transmission is held off.

The CTS line may be set high or low to hold off

communication from a sending device. The sender must

recognize the CTS line. Line 400 sets CTS high and 500

sets it low, or to hold off.

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Remote-processing RPC-330 Manuel d'utilisateur Page 14

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