User`s manual

83
CHAPTER 3 COMMUNICATIONS BY THE MODEM FUNCTION
3
3.3 Specifications
3.3.2 Specification of connectable modems/TAs (terminal adapters)
The following table lists the specification of modems/TAs that can be connected to the Q series C24 side when the
modem function is used.
(1) Specification and precautions for the connectable modems
(a) Modem specification
*1 The following are the functions of the modem itself that become available by issuing the AT commands to the modem.
See the modem manual for details.
 Error correction
• When a noise occurs on the line, scrambled data may appear due to interrupted communication data. The error
correction function is intended to suppress effects from such noises.
• If an error such as scrambled data is detected by the error correction, the modem retries the transmission. When
the number of retries has exceeded the modem's limit, the modem determines that communication cannot be
performed in that environment and disconnects the line.
• Both modems must support the MNP4 or V.42 protocol.
 Data compression
• This function compresses data to be sent prior to transmission, and inflates the compressed data upon reception,
then forwards to the terminal.
• The data compression is effective for the execution speed at a maximum of 200% for the MNP5 and 300% for the
V.42bis.
• Both modems must support the MNP5 or V.42bis protocol.
 Flow control (RS/CS control)
When communication between a modem and terminal is faster than between two modems, the flow control is performed
in the following order:
• The modem transmits data to the partner by storing the data from the terminal in the modem buffer.
• When the buffer in the modem becomes almost full, the modem outputs a data-transmission temporary stop
request (CS (CTS) signal = OFF) to the terminal. The terminal then stops data transmission to the modem when
the data-transmission temporary stop request (CS (CTS) signal = OFF) is received. Even while the terminal
pauses data transmission, the modem continues to send data to the partner.
• When a free space is present in the modem buffer, the modem outputs the data-transmission resume request (CS
(CTS) signal = ON) to the terminal. The terminal then resumes data transmission to the modem when the data-
transmission resume request (CS (CTS) signal = ON) is received.
*2 Modems that turn on the CD (DCD) signal simultaneously cannot be used.
Item
Specifications
Remarks
When using the
subscriber's telephone
line/office telephone system
When using a manual line
connection/cellular phone
Modem-to-modem
communication
specification
Connection line Analog 2-line 
Initialization Hayes AT command compatible Page 134, Section 3.4.3
Telephone line A line compatible with NTT communication protocol
 Page 80, Section 3.2.4
regarding the restrictions
Communication
standard
ITU-T V.34/V.32bis/V.32/V.22bis/V.22/V.21/V.fc

Bell 212A/103
Error correction
*1
MNP Class 4 and 10 compliant
ITU-T V.42 compliant
Data
compression
*1
MNP Class 5 compliant
ITU-T V.42bis compliant
ANS-ORG mode switch  Mode switching required
Q series C24-to modem
communication
specification
Q series C24-side
connector (RS-232)
9-pin (female) D sub  User's Manual (Basic)
DR signal control Only the DR (DSR) signal must be able to turn on
*2
Other Compatible with the Q series C24 specification
 Page 82, Section 3.3.1,
 User's Manual (Basic)