Communication

COMMUNICATIONVoiceLanguageBetween people

COMMUNICATIONBetween machinesPhysical LayerCommunication Protocols

Physical layerUnitronics PLCs support several physical layers:

RS232 (2 units; up to 16 meters) RS485 (up to 32 units; up to 1200 meters daisy chain) CANbus (up to 64 units; up to 1000 meters daisy chain) Ethernet (up to 100 meters from device to HUB Star(General Review

ProtocolsUnitronics PLCs support several Protocols:

Pcom (Unitronics private protocol) MODBUS CANbus (Unitronics ISC, UniCAN, CANOpen) MODBUS IP Option to implement third party protocols (RS232/485 and Ethernet)General Review

Hardware Review NoneSomemodels1 port, RS232M90Ethernet card (optional)NoneNoneEthernetAll modelsSomemodelsSomemodelsCANbus2 ports, RS2321 optional port, RS232/4852 ports, RS232/4851 port, RS232/485Serial V230/260/280/290V120M91/91-2Jazz (option)V5702 isolated ports, RS232/485YesEthernet card (optional)

Protocol Review

Physical LayersRS232Communication parameters Baud rate: 300 ~ 115200 bps Start bit:always 1bit Data bits:7 or 8 data bits Parity check:Even, Odd, None 1 bit Stop bits:1, 1.5 or 2 bitsCommunication word can be only 10 or 11 bitsAll communication parameters in both sides must be exactly the same!M90/91 & Jazz default parameters: 9600, 7, Even, 1Vision default parameters: 57600/115200, 8, None, 1

Physical LayersRS485 Communication in daisy chain network up to 32 devices Balanced half duplex signal (RS485)Two wires A (Rx/Tx+) and B (Rx/Tx-); Up to 1200 meters - twisted shielded pair cable; Supported by Jazz (optional) M91-2-xx, V120, V2xx (optional) controllers, V570

Physical LayersRS485 Communication parameters same as in RS232 Addressing (Unitronics OPLC) ID 65 ~ 254

Protocol Review The Pcom Protocol All Unitronics PLC operating systems are embedded with the Pcom protocol. Pcom enables Unitronics PLCs as slave devices, enabling them to be accessed by incoming communications via all ports. The Pcom protocol is also the protocol that we use for programming, remote access, and data acquisitionThe Pcom protocol is addressable by nature (part of the protocol) and so it can work over a network as well. The Pcom protocol is given free as a DLL with all documentation and help for people to implement inside their software.

Protocol review The Pcom protocol Two other implementations of the Pcom protocol are the DDEserver and the OPCserver. DDEserver and OPCserver are PC based applications that can, on one hand, take information from our PLCs and on the other give out this information in a format that other Windows based applications can understand (like SCADA systems for example). Our DDE and OPC server are given free on the installation CD of both U90Ladder and VisiLogic, or can be downloaded from our website.

Protocol Review The MODBUS protocol One of the most common protocols in the market is the MODBUS protocol. The MODBUS protocol, originally made for Modicon PLCs, is shared by many SCADA applications, drives and other equipment. In order to support MODBUS, the PLC has to conform with the MODBUS addressing structure. MODBUS is a master-slave protocol, and can run over RS232/485 as well as Ethernet. There are different versions of Modbus. We support Modbus RTU (binary) over RS232/485 and Modbus IP over Ethernet

What do you think? Lets make a small application that implements MODBUS communication between two PLCs.One PLC will act as master PLC, and the second will act as slave.

Physical Layers CANbus Unitronics CANbus runs on the same physical layer as A.B.s DeviceNet, but uses a different protocols.

A CANbus network can include up to 63 PLCs and mix different models of M90/91as well as Vision.

CAN bus wiring Specifications

CAN bus Cable Lookout

Protocol Review CANbus as BridgeA PC can talk to a Vision via the RS232 serial port.The PLC can act as a bridge between RS232 and CANbus.Up to 63 PLCs can be connected in a CANbus net and then linked via the bridge to a PC. The PC can see each PLC in the CANbus net.The bridge controller needs no special programming or hardware. Any random controller in the net can act as the bridge.This connection also allows software download and upload to every PLC on the net.In the case of a mixed network (M90/91 and Visions) the bridge controller must be a Vision PLC.

CAN bus Network to PC

Protocol Review Protocols over CANbus PLCs on the CANbus network can also talk among themselves.

In Unitronics protocols ISC and UniCAN, the PLCs are both master and slave. ISC and UniCAN are Multimaster protocolsCANOpen is protocol, supported by a lot of third party devices. Its supported only by Vision series OPLC. Unitronics acts as Master. One Unitronics controller can be connected to few other devices.

Lets build a small application that connects two PLCs in CANbus - UniCAN and allows them to read information from each other.What do you think?

Modem

All Unitronics PLCs support modem connection. Connecting to the PLC from afar enables one to remotely download, debug and upload applications.Remote Communication

Unitronics PLCs support 4 types of modems:PSTN modem (Plain Simple Telephone Network)GSM/GPRS modem (wireless)CDMA modemRF modemsRemote Communication Modem

When we want to connect a PC to a PLC via modem we have 3 aspects to look at:PLC to modemModem to modemModem to PCThe cable connecting the PLC and modem is the Unitronics programming cable, accompanied by a special connector (each modem has its own). The modem has to be prepared, via software, before it is connected.The connection can be established both from the PC and the PLCRemote Communication Modem

SMSOne of the major advantages of cellular modems is the ability to send short text messages (SMS).SMS is a global standard that allows the sending of characters from one phone to the another. The phones can either be on the same network or on different ones (depending on agreements between the cellular providers).Remote communication

The ability to connect the PLC to a cellular phone opens up a wide variety of applications. Basically, a PLC connected to a GSM modem can receive pre-programmed messages and act accordingly. The PLC can also respond by sending a message to a cellular phone. Remote Communication SMS

Another important part of Remote Access is theRemote Communication Ethernet

Unitronics Vision230/260/280/290/570 all support Ethernet. Our Ethernet Card offers 4 sockets and works with both TCP/IP and UDP/IP.The Ethernet card can work with speeds of either 10 or 100Mbps.The PLC supports the MODBUS over TCP protocol and uses this as the connection to SCADA systems and among PLCs.

Remote Communication Ethernet

As part of Unitronics philosophy, we provide a special software utilities -free with our Software CDs.This utility enables PC to PLC modem connection and remote accesseven without VisiLogic or U90Ladder software. Software UtilitiesRemote Communication

This easy to use tool is in fact a very simple SCADA It enables monitoring and operate of the controller from PC. Remote access supports RS232/485, Modems, Ethernet and CAN bus via bridge.

Remote accessRemote Communication

This tool is especially designed to make automated reading of Data Tables from Remote OPLC to PC.Supports RS232/485, modem connection and Ethernet.

DataXportRemote Communication

Unitronics Thank You

RS485 Wiring Specifications

CAN bus Cable Lookout

RS232/RS485 Port Pinout M91-19-4xx, the new M91-2-xx and Vision series controllers have common RS232/485 COM ports.RS232 or RS485 are jumper selectable.

In order to establish communication we need to deal with 4 elements:General Review

What's the maximum number of PCs that can look simultaneously at one PLC?Lets make a small application that communicates between two PLCs over the Ethernet. What do you think?

Unitronics PLCs support a wide range of baud rates:

9600-57600bps for serial communication 50-1000Kbps For CANbus 10/100Mbps for EthernetBaud rateGeneral Review

Unitronics PLCs support different structures:

10/11 for serial 11 bit format TCP or UPD for EthernetData structureGeneral Review

Physical LayersRS232 Communication between two devices only Unbalanced full duplex signal Up to 16 meters Supported by all Unitronics controllers

Physical LayersRS232Two types of communicating devices:DTE (Data Terminal Equipment)ComputersControllersDCE (Data Circuit-Terminated Equipment)PrintersModemsMale DB9Female DB9

Physical LayersRS232DTE signals and pin-outDCE signals and pin-outComputerUnitronics OPLC

Can I centralize information from 9 PLCs on the CANbus network into one PLC?I have a sensor that runs on CANopen. Can I connect it to the CANbus network and read the value inside the PLC?What is the maximum number of PCs that can simultaneously look at the data within a Unitronics CANbus network?What do you think?

A modem, in general, has two modes of operation:Command modeData modeIn Data mode, the modem is a tube conveying data between two points. When we talk of modems in a network (like RF), we must ascertain that the modem does not add anything to the data; if it does, we must take it into consideration in the protocol. In order to enter data mode, the modem has to connect to the other modem (or the network), and at the end of the session it must disconnect.In Command mode, one can use the AT commands to communicate with the modem, change settings, or make the modem perform different operations. The modem stays in command mode until someone connects to it, or gives the dial command.Remote Communication Modem

What conditions have to be met in order to download an operating system over a modem?Can I use internal modems on the PC? What selections do I have to make in the PC modem configuration?Can I be connected, over modem, to more than one PLC at a time?What do you think?

I want to have a system that will call me every time there is an event, can I do that? What will happen when the system calls?If I want to connect to one of my PLCs for debugging, can SMS messages still flow in and out of the modem?Can an SMS be considered as a real-time event from the system?What do you think?