T
[email protected]
- Jan 1, 1970
- 0
Hi all
I'm trying to solve a major problem we have at work. We have a master
unit on the surface and multiple sensors in the water. For the past 10
years they have been networked by RS485 operating at 1.5 Mbps. Our
production people have gotten the sensors to communicate with the
surface unit at distances well over 100 m with clever impedance
matching tricks.
However, we'd like to switch to Ethernet for robustness and for better
realization of an ideal "single master, multiple sensors" model.
Using RS485, we often use a "wet Y" or "wet W" to split the RS485 lines
into 2 or 3 paths that are connected to sensors a short distance from
the junction (~1 m or so). I want to figure out how to implement this
same functionality with Ethernet (either coax or twisted pair).
We have our cables custom-made. They are armored and quite robust.
I'd like to avoid putting any electronics inside the Y or W junction.
For twisted pair, I've heard that you should not unravel the pair more
than an inch or you'll severely compromise the data integrity.
I'm hoping that perhaps the old coax approach to Ethernet might be a
reasonable solution since everything was tied together in an analog
fashion with BNC connectors. However, it a daisy-chain configuration
rather than a star configuration, which is really what I'm hoping to
achieve (perhaps with clever impedance matching techniques?).
Am I barking up the wrong tree? If I search hard enough am I likely to
find a solution, or am I just headed in the wrong direction? Are there
any Ethernet tutorials that you've found helpful at a hardware level?
Ultimately, I'm going to have to put the whole thing together myself,
from hardware TCP/IP stack to MAC to PHY, so I'm also interested in
recommendations for hardware solutions (I'm hoping for at least 5 Mbps
throughput).
Thanks in advance for the help.
Todd
I'm trying to solve a major problem we have at work. We have a master
unit on the surface and multiple sensors in the water. For the past 10
years they have been networked by RS485 operating at 1.5 Mbps. Our
production people have gotten the sensors to communicate with the
surface unit at distances well over 100 m with clever impedance
matching tricks.
However, we'd like to switch to Ethernet for robustness and for better
realization of an ideal "single master, multiple sensors" model.
Using RS485, we often use a "wet Y" or "wet W" to split the RS485 lines
into 2 or 3 paths that are connected to sensors a short distance from
the junction (~1 m or so). I want to figure out how to implement this
same functionality with Ethernet (either coax or twisted pair).
We have our cables custom-made. They are armored and quite robust.
I'd like to avoid putting any electronics inside the Y or W junction.
For twisted pair, I've heard that you should not unravel the pair more
than an inch or you'll severely compromise the data integrity.
I'm hoping that perhaps the old coax approach to Ethernet might be a
reasonable solution since everything was tied together in an analog
fashion with BNC connectors. However, it a daisy-chain configuration
rather than a star configuration, which is really what I'm hoping to
achieve (perhaps with clever impedance matching techniques?).
Am I barking up the wrong tree? If I search hard enough am I likely to
find a solution, or am I just headed in the wrong direction? Are there
any Ethernet tutorials that you've found helpful at a hardware level?
Ultimately, I'm going to have to put the whole thing together myself,
from hardware TCP/IP stack to MAC to PHY, so I'm also interested in
recommendations for hardware solutions (I'm hoping for at least 5 Mbps
throughput).
Thanks in advance for the help.
Todd