esp-protocol Posted January 4, 2007 Share Posted January 4, 2007 Can any clever person tell me whether they would use cat5 cable on an RS 485 network?? The runs are not particularly long (typically 25m between devices) but it is in a crowded computer room. Thanks Dave Link to comment Share on other sites More sharing options...
breff Posted January 4, 2007 Share Posted January 4, 2007 Its ok for camera telemetry, whats it for? The opinions I express are mine and are usually correct! (Except when I'm wrong)(which I'm not) Link to comment Share on other sites More sharing options...
james.wilson Posted January 4, 2007 Share Posted January 4, 2007 technically its ok but as its solid core it isnt designed for our terminals. Is used prefer not to but i dont see a real technical reason (the twists are right) apart from it not being screened but technically a balanced 485 shouldnt need screening anyway (i said 'technically' guys) securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
amateurandy Posted January 4, 2007 Share Posted January 4, 2007 Can any clever person tell me whether they would use cat5 cable on an RS 485 network??The runs are not particularly long (typically 25m between devices) but it is in a crowded computer room. Thanks Dave For RS-485 the terminating resistors have to match the cable impedance, so you might cause problems unless you get them both right. Read this: http://www.maxim-ic.com/appnotes.cfm?appno...63&CMP=WP-1 Link to comment Share on other sites More sharing options...
james.wilson Posted January 4, 2007 Share Posted January 4, 2007 lol andy, i have been saying this for years but apparantly the laws of rs485 only apply to galaxys not texecoms securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
esp-protocol Posted January 4, 2007 Author Share Posted January 4, 2007 Well.... Its being used for a small BMS system to monitor room temp and humidity stats, and a lot of volt free contacts, we are also picking up some display meters using modbus. We were goiing to use a two pair twisted individually screened cable but the main contractor has now supplied cat 5 cable and I was just trying to head off any forseeable problems.... thanks Link to comment Share on other sites More sharing options...
james.wilson Posted January 4, 2007 Share Posted January 4, 2007 youe be fine but dont put multiple buses in the same cat 5, that will probably cause you grief unless your resistors are spot on securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
esp-protocol Posted January 4, 2007 Author Share Posted January 4, 2007 youe be fine but dont put multiple buses in the same cat 5, that will probably cause you grief unless your resistors are spot on Top man......... we'll see what happens then. Thanks Link to comment Share on other sites More sharing options...
Drew Posted January 5, 2007 Share Posted January 5, 2007 We recommend it. Ours is a full duplex (two channel, four core) RS485 bus which runs at over 100kbaud. We have tested it extensively, and it works over 1,000m with Net2. Having said that, all systems are different in the way in which they cope with data errors, so trying it is good. A useful tip is to connect spare pairs in the CAT5 cable as if they were a screen. That is a very effective method for reducing interferance. Drew Hoggatt Managing Director Paxton Access Ltd Follow this link for important legal information Link to comment Share on other sites More sharing options...
esp-protocol Posted January 5, 2007 Author Share Posted January 5, 2007 We recommend it.Ours is a full duplex (two channel, four core) RS485 bus which runs at over 100kbaud. We have tested it extensively, and it works over 1,000m with Net2. Having said that, all systems are different in the way in which they cope with data errors, so trying it is good. A useful tip is to connect spare pairs in the CAT5 cable as if they were a screen. That is a very effective method for reducing interferance. drew,,,, a top tip that I will be sure to remember.... thanks Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.