Mettler Toledo ACM500 Guia De Instalacion página 13

1.9.2. PLC Interfaces
The IND560x PLC interface options available through the ACM500 include Analog Output, A-B RIO,
DeviceNet, EtherNet/IP, Modbus-TCP and PROFIBUS DP.
1.9.2.1. Analog Output
Analog Output refers to the representation of an internal system variable using a proportional
electrical signal. Analog Output can be used to transmit a measured value, such as the gross or net
weight or a rate. Another use for the Analog Output is as a control signal for some external device,
such as a control valve, where the amount of valve opening is proportional to the analog signal
commanding its operation. Such outputs are usually used to control the flow rate of material into or
out of a vessel.
Both 0-10 volt DC and 4-20 mA signals are provided. Additional details of this interface can be
found in the PLC Interface Manual on the ACM500 Documentation CD.
1.9.2.2. Allen-Bradley (A-B) RIO
The A-B RIO option enables data exchange by bi-directional communications using the Discrete
Data Transfer or Block Transfer mode. The terminal provides a communication exchange with the
PLC approximately 20 times per second utilizing the Allen-Bradley Discrete Data Transfer protocol.
This communication is a high-speed, real-time message interface between the terminal and the PLC
for process control. Division, integer, and floating point values are supported.
The A-B RIO interface also supports Block Transfer mode for transmission of larger amounts of
data. Additional details of this interface can be found in the PLC Interface Manual on the ACM500
Documentation CD.
1.9.2.3. DeviceNet
DeviceNet is an RS-485 based network utilizing CAN chip technology. The network can be
configured to run up to 500Kbits per second depending on cabling and distances. Messages are
limited to 8 un-fragmented bytes. The IND560x implementation of DeviceNet does not support
fragmented messages - all messages are 8 bytes or shorter. The network is capable of supporting
up to 64 nodes including the master.
1.9.2.4. EtherNet/IP
EtherNet/IP, short for "EtherNet Industrial Protocol," is an open industrial networking standard that
takes advantage of commercial, off-the-shelf EtherNet communication chips and physical media.
This networking standard supports both implicit messaging (real-time I/O messaging) and explicit
messaging (message exchange). The protocol is supported by ControlNet International (CI), the
Industrial Ethernet Association (IEA) and the Open DeviceNet Vendor Association (ODVA).
1.9.2.5. Modbus TCP
Modbus/TCP is used to establish master-slave/client-server communication between intelligent
devices. It is an open standard network protocol, widely used in the industrial manufacturing
environment. The ModbusTCP protocol takes the Modbus instruction set and wraps TCP/IP around
it.
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