When it comes to transmitting process variables, 4-20 mA is by far the most popular method. Digital fieldbuses such as PROFIBUS or PROFINET, however, are said to be more accurate and generally better than 4-20 mA. What isn’t discussed very often, however, is the extent of how much more accurate they are. This topic is the elephant in the control room.
PROFIBUS DPV1 Alarms are a special kind of extended diagnostic. Compared to normal extended diagnostics, Alarms require an additional acknowledgment “handshake” between the master (controller) PLC or DCS and the slave device.
Did you know that over 100 members now belong to the IO-Link community? IO-Link has established itself in the market faster than almost any other communication technology. At the market launch in 2009, there were 41 member companies to start. Now with the addition of Weiss Robotics in October, the 100th company has joined the member community.
Did you know that IO-Link can transmit up to 32 bytes in one cycle? The IO-Link interface standardized in IEC 61131-9 is based on simple serial data transmission via conventional connecting cables. With IO-Link, it is over exactly this cable that data packets are exchanged cyclically between the IO-Link master and an IO-Link device packed in one protocol.
We often use an age old catch phrase during our PROFINET one day classes, “But wait, there’s more!” when we get to the latter part of the day. At that time we’ve usually covered the standard PROFINET application functionality and continue talking about additional PROFINET features and options. We’ve found that most engineers and developers don’t realize what the optional features of PROFINET are and their purpose. Here is a list of those optional features and what they do.
We often get the question: Why doesn’t PROFINET use Dynamic Host Configuration Protocol (DHCP) for IP address assignment as DCHP is used extensively in the office? Answer: DHCP could be used, optionally, but there are some differences you should know between DHCP and PROFINET DCP.
Did you know that IO-Link protects against incorrect device replacement? If a sensor has to be replaced, this is usually done at a hectic pace since the machine must go back into operation as quickly as possible. Often, there is no specially trained staff available for this task. For this reason, IO-Link takes a different course. Developed as an interface "by practitioners for practitioners", it has a variety of integrated options to maximize the ease and reliability of device replacement.
DCP is part of the PROFINET protocol suite and stands for “Discovery and Configuration Protocol”. It is used by the engineering tool and controller to discover devices, identify device information, and configure device settings such as PROFINET device name and IP address on a PROFINET network. PROFINET DCP is an Ethernet link layer protocol and offers multiple services. (more…)