# Allen Bradley PLC networks **URL:** \ **Category:** Allen Bradly\ **Tags:** plc, instrumentation\ **Created:** [November 13, 2017, 6:49pm UTC](https://forumautomation.com/t/allen-bradley-plc-networks/2637 "2017-11-13T18:49:45Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![sivaranjith](https://forumautomation.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@sivaranjith](https://forumautomation.com/u/sivaranjith)\ **Post date:** [November 13, 2017, 6:49pm UTC](https://forumautomation.com/t/allen-bradley-plc-networks/2637/1 "2017-11-13T18:49:46Z")
There are different PLC networks used to connect devices to an Allen Bradley system, Data Highways and Control Net. Data highways are DH, DH+, DH 485. > **DH:** - DH is a local area network - Maximum number of devices can be connected: 64 - DH link implements peer-to-peer communication through a scheme called floating master to provide each node equal access to become the master - A DH transmit 57.6K bits of data per second. > **DH+ :** - DH+ link is similar to the DH link, the only difference is that in the number of nodes, where the maximum number of allowed nodes are 15. - Maximum number of allowable devices are 64 - Speed of data transmit ranges from 57.6, 115.2, or 230.4K bits per second. - DH+ is also implemented a peer-to-peer communication > **DH485:** - DH485 is a peer-to-peer programming data acquisition link with 32nodes. - Here peer-to-peer communication uses a token-passing scheme to rotate link master among the nodes. - DH 485 Network using AIC+ ![](https://cdn.forumautomation.com/original/1X/a773edd949b4781136a29085a066e224c0663b4a.png) > **Control Net:** - The ControlNet network provides high-speed transmission of time-critical I/O and interlocking data and messaging data. - This data transfer capability enhances I/O performance and peer-to-peer communication in any system or application - The ControlNet network is highly deterministic and repeatable and remains unaffected as devices are connected or disconnected from it.