Ricoh M160 Service Manual page 746

Bit Switches - 4
No Function
DIS detection number
(Echo countermeasure)
0
0: 1
1: 2
1 Not Used
V.8 protocol
2 0: Disabled
1: Enabled
ECM frame size
3 0: 256 bytes
1: 64 bytes
CTC transmission conditions
0: After one PPR signal
4 received
1: After four PPR signals
received (ITU-T standard)
SM
G3 Switch 03 (SP No. 1-105-004)
0: The machine will hang up if it receives the
same DIS frame twice.
1: Before sending DCS, the machine will wait
for the second DIS which is caused by echo on
the line.
Do not change this setting.
0: V.8/V.34 communications will not be
possible.

Keep this bit at "0" in most cases.
0: When using ECM in non-standard
(NSF/NSS) mode, the machine sends a CTC to
drop back the modem rate after receiving a
PPR, if the following condition is met in
communications at 14.4, 12.0, 9.6, and 7.2
kbps.
NTransmit- Number of transmitted frames
NResend- Number of frames to be
retransmitted
1: When using ECM, the machine sends a CTC
to drop back the modem rate after receiving
four PPRs.
PPR, CTC: These are ECM protocol signals.
This bit is not effective in V.34 communications.
90
Comments
Do not set to 0 unless the line
condition is always bad enough to
slow down the data rate to 14.4 kbps
or lower.
M160/M161 Fax Option