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Perdition
Guest
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 Posted:
Sun Nov 06, 2005 5:20 pm Post subject:
Question about an F633 optical modem's level components |
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A description of the modem:
"The FM 633 card is an asynchronous fiberoptic modem, supporting either
a rs-232 or a TTL level communication channel, which enables computers
to communicate with a remotely located device over a dual, fully duplex
fiberoptic communication link".
It then states the data rates as follows:
Rs-232: up to 38kbps
TTL: up to 100kbps
The rs-232 or ttl leveling can be chosen through jumpers on the card
itself. I assumed by TTL it meant the modulation towards the remote
site but then it wouldn't give you a choice of that or the rs-232. By
TTL did they mean that through the RS-232 interface they would only use
transmit and receive pins to sample the data from the DTE at a faster
rate, or is there some other meaning i missed? Thanks for your time
guys :)
P.S. the only interface from the modem to other equipment is an RS-232
port and two ST fiberoptic ports for transmit and receive. |
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Reed
Guest
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| Posted:
Mon Nov 07, 2005 1:20 am Post subject:
Re: Question about an F633 optical modem's level components |
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Perdition wrote:
| Quote: |
A description of the modem:
"The FM 633 card is an asynchronous fiberoptic modem, supporting either
a rs-232 or a TTL level communication channel, which enables computers
to communicate with a remotely located device over a dual, fully duplex
fiberoptic communication link".
It then states the data rates as follows:
Rs-232: up to 38kbps
TTL: up to 100kbps
The rs-232 or ttl leveling can be chosen through jumpers on the card
itself. I assumed by TTL it meant the modulation towards the remote
site but then it wouldn't give you a choice of that or the rs-232. By
TTL did they mean that through the RS-232 interface they would only use
transmit and receive pins to sample the data from the DTE at a faster
rate, or is there some other meaning i missed? Thanks for your time
guys :)
P.S. the only interface from the modem to other equipment is an RS-232
port and two ST fiberoptic ports for transmit and receive.
|
TTL stands for Transistor-Transistor Logic (as opposed to RTL
among others)
see http://en.wikipedia.org/wiki/Transistor-transistor_logic
for good explanation.
In this case a TTL-based device could use the F633 as a "modem"
without the need for another electrical interface, like RS-232, in
between.
BTW, a book that I use/used a lot on now-legacy data comm info is
available used from Amazon for as little a US$5. go to Amazon and
do an author search on "Tugal"; also any texts by William
Stallings would be good info on systems of the time.
--reed |
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Perdition
Guest
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| Posted:
Mon Nov 07, 2005 5:20 pm Post subject:
Re: Question about an F633 optical modem's level components |
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but there is only an rs232 interface in the back of the modem and two
ST fiberoptic slots for tranmission and receiving, how would a TTL
based device interface with the F633? the modem still needs the two
fiberoptic slots for communication with the remote site and all that's
left is the rs232 interface |
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Reed
Guest
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| Posted:
Tue Nov 08, 2005 9:20 am Post subject:
Re: Question about an F633 optical modem's level components |
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Perdition wrote:
| Quote: |
but there is only an rs232 interface in the back of the modem and two
ST fiberoptic slots for tranmission and receiving, how would a TTL
based device interface with the F633? the modem still needs the two
fiberoptic slots for communication with the remote site and all that's
left is the rs232 interface
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Either the "Rs-232" port connector becomes a TTL capable I/O port,
or it could be that TTL mode is only used if the PCB of the unit
is integrated or hard-wired into some other device. You would
probably need specific documentation for the FM633, or trace out
where the signals go if you move the jumpers to the TTL position
to determine which.
--reed |
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