CDPD and/or cell

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Thread Starter

Bob Lockert

I've noticed a lack of comment on CDPD or cell phone usage. Is it being used for SCADA? The technology appears mature and coverage adequate (in my area). However, I hesitate to go down a road others may have abandoned. I'd appreciate any and all comment. Thanks, Bob Lockert Blocke Communications Calgary, Canada
 
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Anthony Kerstens

With the advent of internet enabled PCS phones (and text pagers), I don't see why simple reports couldn't be sent to a phone. I used to have a "Mike" phone (motorola) and played with the email messaging. It seems to work, but messages can take several minutes to arrive. The advantage of the "Mike" system is it integrates telephone, 2-way voice, and email into one unit. Anthony Kerstens P.Eng.
 
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It is done. We have a customer (a big oil pipeline concern in Texas) who is switching *PART* of their RTU management system away from GSM cell phone technology to more direct TCP/IP based WAN technologies. I'm not sure why, but get the feeling the GSM works wonderfully (almost miraculously after years of traditional DIALUP heartburn), but the day-to-day costs are high. So they are switching OUT those RTU sites which can run with the more traditional TCP/IP radio/WAN technologies. Plus I also believe the TCP/IP technologies allow piggy-backing (retrofit) on existing microwave and fiber optics more easily, so they are also expanding faster & cheaper using this route instead of adding more GSM links. They DO LIKE THE GSM LINKS - no doubt about that. I think they just learned it is a costly technology that should be PART - not ALL - of the solution. Regards Lynn August Linse, Senior Product Application Engineer 15353 Barranca Parkway, Lantronix Inc, Irvine CA 92618 [email protected] www.lantronix.com Tel: (949)300-6337 Fax: (949)453-7132
 
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Fred A. Putnam

We can provide this (simple reports sent to a phone). Please contact me if you are interested. -- Fred A. Putnam LABTECH, Suite B9, 2 Dundee Park, Andover, MA, 01810 tel:978-470-0099 x231, mobile: 978-807-7202, FAX:978-470-3338 e-mail: [email protected] web: http://labtech.com
 
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> We have a customer (a big oil pipeline concern in Texas) who is switching *PART* of their RTU management system away from GSM cell phone technology to more direct TCP/IP based WAN technologies. < Lynn, could you explain what you mean by "more direct TCP/IP based WAN technologies"? Don Gussin Siemens Milltronics Process Instruments
 
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I don't usually get to see the remote, but I assume it's things like DSL modems with an Ethernet port etc. I consider them more direct - I guess more "traditional" or common-as-of-today may be alternative terms. My level of involvement is a customer who "Before" has a serial dialup and "Now" has an Ethernet port instead asks how to connect to the serial device by TCP/IP out that new Ethernet port on-site. Best Regards Lynn August Linse, Senior Product Application Engineer 15353 Barranca Parkway, Lantronix Inc, Irvine CA 92618 [email protected] www.lantronix.com Tel: (949)300-6337 Fax: (949)453-7132
 
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I guess I wasn't too clear on the intended uses for CDPD. Lynn, >My level of involvement is a customer who "Before" has a serial dialup and >"Now" has an Ethernet port instead asks how to connect to the serial device >by TCP/IP out that new Ethernet port on-site. > This is not unlike my interest. My 'Before' situation includes both dedicated and dial up remote locations. Some of the remote dial ups have cell modems. But they're all basically serial port to serial port connections. I want TCP/IP but not on an Ethernet card. The downside of cell is that you pay for time and possibly long distance charges (the latter also true of land lines). This precludes continuous connections (call but never hang up). Furthermore, you can't multidrop so a dedicated port and phone line at the host end is required for each device. As I understand CDPD, it is basically IP over cell (I think). The remote CDPD modem has a fixed IP address on the cell (air) side. Some models support TCP and include a TCP/IP stack. Packets received by the modem are stripped of their TCP/IP bytes and passed to the RTU. Data sent by the RTU has the TCP/IP headers etc. added by the stack in the modem and is sent over the network. By providing the equivalent at the host desktop, nearly any native protocol could be wrapped in this manner and provide a virtual connection to the appropriate RTU. In this situation the modem can be 'connected' all the time without time or long distance charges. CDPD charges are based on data volume, so infrequent polling or report by exception strategies can minimize costs. Again, I welcome any and all feedback on this subject. Bob Lockert Blocke Communications Calgary, Canada (403) 286 6711
 
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