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what is null modem ? 2
- Thread starter logi2000
- Start date
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2
- #2
robertjo24
MIS
Quite simply:
A null modem is a cable or connector that allows two DCE or two DTE RS-232 devices to talk directly to each other. Usually the TX and RX pins will be crossed, along with the RTS and CTS. Some null modems will loop the RTS and CTS on each end. RTS and CTS are only required for hardware flow control.
A null modem is a cable or connector that allows two DCE or two DTE RS-232 devices to talk directly to each other. Usually the TX and RX pins will be crossed, along with the RTS and CTS. Some null modems will loop the RTS and CTS on each end. RTS and CTS are only required for hardware flow control.
- Thread starter
- #3
hi,
A specially designed cable that allows a user to connect two computers directly to each other via their communications ports (RS-232 ports). Null modems are particularly useful with portable computers because they enable the portable computer to exchange data with a larger system.
Null Modem Cable Pin-outs and information
Direct Access Australia - Technical Help
Dick Smith Electronics catalogues have wiring info for a null modem cable in the data pages at the back.
Microsoft Knowledge Base articles
Direct Cable Connection Fails with Only NetBEUI Loaded
To set up a direct cable connection
Unable to Connect Using Direct Cable Connection (Win95 to Win98)
From "Doc" <fuzzydave@yahoo.com>
25 PIN D-SUB FEMALE to the Computer. 25 PIN D-SUB MALE to the Serial cable.
Female Male
Function(Pin) (Pin) Function
==========================
Shield Ground (1) - (1) Shield Ground
Transmit Data (2) - (3) Receive Data
Receive Data (3) - (2) Transmit Data
Request to Send (4) - (5) Clear to Send
Clear to Send (5) - (4) Request to Send
Data Set Ready (6) - (20) Data Terminal Ready
Data Terminal Ready (20) - (6) Data Set Ready
Ground (7) - (7) Ground
A specially designed cable that allows a user to connect two computers directly to each other via their communications ports (RS-232 ports). Null modems are particularly useful with portable computers because they enable the portable computer to exchange data with a larger system.
Null Modem Cable Pin-outs and information
Direct Access Australia - Technical Help
Dick Smith Electronics catalogues have wiring info for a null modem cable in the data pages at the back.
Microsoft Knowledge Base articles
Direct Cable Connection Fails with Only NetBEUI Loaded
To set up a direct cable connection
Unable to Connect Using Direct Cable Connection (Win95 to Win98)
From "Doc" <fuzzydave@yahoo.com>
25 PIN D-SUB FEMALE to the Computer. 25 PIN D-SUB MALE to the Serial cable.
Female Male
Function(Pin) (Pin) Function
==========================
Shield Ground (1) - (1) Shield Ground
Transmit Data (2) - (3) Receive Data
Receive Data (3) - (2) Transmit Data
Request to Send (4) - (5) Clear to Send
Clear to Send (5) - (4) Request to Send
Data Set Ready (6) - (20) Data Terminal Ready
Data Terminal Ready (20) - (6) Data Set Ready
Ground (7) - (7) Ground
- Status
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