Canon fax basic 2000 サービスマニュアル

G3 FACSIMILE COMMUNICATIONS

5–130

• RNR and RR

On receivers whose printing speed is slower than the data receive speed,

the receive buffer sometimes becomes full or busy. In this case, reception

of the next block is not possible until new free memory appears after print-

ing of already received blocks has ended. If this happens, the receiver out-

puts RNR to communicate to the transmitter that the next blocks cannot be

received temporarily (receiver is busy).

When the transmitter receives RNR, RR is repeatedly output to inquire as

to the state of the receiver. When the receiver receives RR, RNR is

returned for the period that the receiver is busy. When the receiver no

longer is busy due to end of printing, for example, MCF is output to com-

municate that the next block can be received. The transmission times of

RNR and RR are determined by timer T5. On facsimiles having a small

page buffer, instances where ##753, ##758 and ##783 errors frequently

occur can be remedied by lengthening the timer T5 setting.

Fig. 5-89 RNR and RR

Calling Side (transmitter)

Called Side (receiver)

Frame 0

Frame 1

Frame 255

Transmission of
1st page

Frame

Transmission
of 2nd page

Line disconnected

Bloc

receiv

dur

ing

this

per

iod

are

being

inted.

"Received
the page."

Frame

Frame 1

Frame 0

Frame

"Are you ready?"

"Not ready to

receive"

"Not ready to

receive"

"Not ready to

receive"

PPR

PPS-MPS

RNR

2400bps

RNR

PPS-MPS

RNR

MCF