Multi-Tech Systems MMV1600 owner manual Enq/Ack, Dtr

data	transfers	are			regulated
	data is lost.
			MUX INITIATED
			FLOW CONTROL
				DATA
			Channel		Mux
			Device
			Flow control stops the
			input of data to the mux

so that no

CHANNEL DEVICE

INITIATED PACING

DATA

Channel

MuxDevice

Pacing stops the output of data from the mux

ENQ/ACK

These

two

commands

control

the

selection

of

a

special

flow

Flow Control

control

system

used

in

Hewlett

Packard

computer

systems.

It

is

sometimes

referred

to

as

Enquire/Acknowledge

flow

control

F3-F4

because it’s based on the computer sending an inquiry (ENQ)

and then expecting an

acknowledgment

(ACK).

F3

turns

on

this

feature and F4 turns off the feature.

Pacing

The

Pacing

Control

command

(F5-on,

F6-off)

is

the

means

used

Control

to

control

data

flow

to

channel

devices.

Pacing

is

necessary

when

devices

operating

on

a

mux

channel

require

more

than

one

F5-F6

character

time

to process

the

data,

the

pacing

commands

initiate

control

so

that

data

is

not

lost

in

the

transfer

process.

The

MultiMux is shipped with pacing off and it will have to be turned

On if your

channel

device cannot accommodate the data volume.

The pacing method used is determined by the type of flow

control.

Pass EIA

The

Pass

EIA

Signal

commands

(F7-on,

F8-off)

are

the

com-

Signals

mands

that

enable

or

disable

individual

channels

to

receive

EIA

control

signals

through

the

MultiMux.

Since

in

normal

interactive

F7-F8

operations,

the

existence

of

a

multiplexer

should

be

transparent

to

individual

users,

the

Pass

EIA

Signals

command

will

allow

terminals

to

operate

as

if

they

were

connected

directly

to

a

communications

line

and

not

through

a

multiplexer.

This

is

done

by

allowing

selected

pins

(signals)

on

one

mux

to

be

passed

through

to

selected

pins

(signals)

on

a

second

remote

mux.

The

following

diagram

shows

how

the

Pass

EIA

Signals

command

routes the selected signals:

MultiMux

(A)

IN 4

IN 20

IN 25

OUT 8

OUT 6

UT 22

Composite Link

Facility

(Effect of the

PASS EIA

Signal

F7

Command)

MultiMux

(B)

8 OUT

6 OUT

22 OUT

4 IN

20 IN 25 IN

Pass

The

Pass

Xon/Xoff

commands,

(F9-enable,

F10-disable),

are

Xon/Xoff

active

only if Xon/Xoff flow control

is

active.

Also

called

the

“Pass

Through”

commands,

they

enable

or

disable

the

MultiMux

from

F9-F10

passing

through

Xon/Xoff

flow

control

signals.

In

the

Enable

mode,

the

MultiMux

will

obey the

Xon/Xoff

commands

and

pass

	them on to the channel device. When this command is enabled,						a	message		"TO
PREVENT DATA LOSS TO A PRINTER OR			OTHER PERIPHERAL WE RECOMMEND USING FLOW
	CONTROL AND PACING, NOT PASS XON", is sent to the						channel device. In the
Disable		mode,			the				MultiMux
	will	obey the	Xon/Xoff commands		and	not	send	them	to	the
	channel device. The default condition is for Xon/Xoff Pass						Through to be disabled
and it normally should remain disabled.			However, in situations such as a slow data rate of a channel
device, disabling the passing of Xon/Xoff signals may improve				throughput by utilizing buffers in the mux.
Inverted	The	Inverted DTR Commands		(F11	and	F12)	work	in	conjunction
DTR	with Pacing Control and change the way the MultiMux reacts to						the	DTR	signal. With