Mitsubishi Electric MELSEC iQ-RJ71C24-R4 - Considerations for System Configurations

7 COMMUNICATIONS BY THE MODEM FUNCTION
7.2 System Configuration
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Considerations for system configurations
The following shows considerations for the system configurations to perform data communication with a target device via
public line, an office telephone system or digital line (ISDN) using the modem function.
Usable C24 interface
• The modem function can be used for the RS-232 interface only.
• For the RJ71C24-R2, the modem function can be used for only either one of the two RS-232 interfaces.
• Interactive data communication via two interface of C24 (interlink operation) is not available.
Connectable modem/TA
Only the modems/TA shown below can be used for the C24 RS-232 interface to use the modem function.
MELSEC iQ-R Serial Communication Module User's Manual (Startup)
Number of connectable modems/TAs
Only one modem/TA can be connected to the C24 RS-232 interface to use the modem function.
Modem/TA connection cables
• Perform the wiring connection as designated on the modem/TA side for connection between C24 and modem/TA.
• For the RS-232 interface of C24, a D-sub 9-pin connector (female) is used.
For the connection cable of C24 side, refer to the following manual.
(MELSEC iQ-R Serial Communication Module User's Manual (Startup))
Modem/TA installation
• Install the modem/TA according to the modem/TA manual.
Installing it in an area where a lot of noises are generated may cause malfunctions.
• In order to prevent the effects of noise and power surges, do not connect near or tie the cable together with a main circuit
line, high-voltage line or load line other than for the programmable controller with the modem/TA connection cable.
Connectable lines
• The connections with the following lines, which are equivalent to NTT communication protocol are available.
Perform connection tests beforehand and confirm that connection is possible.
Public line or office telephone system of analog two-line method
Digital line (ISDN)
• It is not possible to connect to call-waiting lines, in order to avoid data errors or automatic line disconnection due to the call-
waiting interrupt tone.
• Avoid connections with party-line telephones to avoid interrupted calls during communication.
• If an alert sound is sent at fixed intervals from the communication machine to prevent long-term calls, data corruption may
occur.
Transmitting a response for normal/abnormal data reception between devices, and performing transmission retry
processing when any abnormality is detected is recommended.
• Refer to the manuals for a modem/TA for connection from a modem to public line/office telephone system, or for connection
from a TA to a digital line.