Cip - communications capabilities, Cip implicit assemblies – Watlow EZ-ZONE PM User Manual
Page 85
Watlow EZ-ZONE
®
PM Limit Controller
•
82
•
Chapter 8 Features
CIP - Communications Capabilities
With the introduction of CIP a user can now collect data, configure a device and control industrial devices.
CIP is an open protocol at the application layer fully managed by the Open DeviceNet Vendors Association
(ODVA,
). Being that this is an open protocol there are many independent vendors offer-
ing a wide array of devices to the end user. CIP provides the ability to communicate utilizing both implicit
messaging (real-time I/O messaging), and explicit messaging (information/configuration messaging). For im-
plicit communications using a PLC, simply configure the PM assembly size into the I/O structure of the PLC
CIP Implicit Assemblie Structures
). The assembly structures can also be changed by the user.
Explicit communications requires the use of specific addressing information. DeviceNet requires that the
node address be specified where EtherNet/IP requires just the Class, Instance and Attribute.
• Node address or MAC ID (0 - 63, DeviceNet only)
• Class ID (1 to 255)
• Instance ID (0 to 255)
• Attribute ID (1 to 255)
EtherNet/IP and DeviceNet are both based on CIP and use the same addressing scheme. In the following
menu pages notice the column header identified as CIP. There you will find the Class, Instance and Attri-
bute in hexadecimal, (decimal in parenthesis) which makes up the addressing for both protocols. The Watlow
implementation of CIP does not support connected explicit messages but fully supports unconnected explicit
messaging.
Rockwell Automation (RA) developed the DF1 serial protocol within the framework of the PCCC applica-
tion protocol. With the introduction of CIP, the PCCC protocol was encapsulated within it to enable continued
communication over Ethernet to the legacy RA programmable controllers, e.g., SLC, Micrologic and PLC-5
controllers equipped with Ethernet capabilities. The Watlow implementation of CIP also supports the PCCC
protocol.
EtherNet/IP (Industrial Protocol) is a network communication standard capable of handling large amounts
of data at speeds of 10 Mbps or 100 Mbps, and at up to 1,500 bytes per packet. It makes use of standard off-
the-shelf Ethernet chip sets and the currently installed physical media (hardware connections). DeviceNet
was the first field bus offering of the ODVA group and has been around for many years. DeviceNet can com-
municate at 125, 250 and 500 kilobytes per second with a maximum limitation of 64 nodes (0 to 63) on the
network.
Note:
If the control is brought back to the factory defaults the user configured assemblies will be overwritten.
Note:
The maximum number of implicit input/output members using DeviceNet is 200. When using EtherNet/IP
the maximum is 100.
CIP Implicit Assemblies
Communications using CIP (EtherNet/IP and DeviceNet) can be accomplished with any PM Integrated con-
trol equipped with either DeviceNet or EtherNet/IP communications cards. As was already mentioned, read-
ing or writing when using CIP can be accomplished via explicit and or implicit communications. Explicit com-
munications are usually executed via a message instruction within the PLC but there are other ways to do
this as well outside of the focus of this document.
Implicit communications is also commonly referred to as polled communications. When using implicit com-
munications there is an I/O assembly that would be read or written to. The default assemblies and the as-
sembly size is embedded into the firmware of the PM control. Watlow refers to these assemblies as the T to
O (Target to Originator) and the O to T (Originator to Target) assemblies where the Target is always the EZ-
ZONE PM controller and the Originator is the PLC or master on the network. The size of the O to T assem-
bly is fixed at 20 (32-bit) members where the T to O assembly consists of 21 (32-bit) members. All assembly
members are user configurable with the exception of the first T to O member. The first member of the T to
O assembly is called the Device Status, it is unique and cannot be changed. If the module has been properly
configured when viewing this 32-bit member in binary format bits 12 and 16 should always be set to 1 where
all of the other bits should be 0. The 20 members that follow Device Status are user configurable. The Ap-
pendix of this User's Guide contains the PM implicit assemblies (See Appendix:
).