Omega A2400 manual Chapter Transparent Mode, Transparent Mode Functions

Page 60

Chapter 10

Transparent Mode

The A2400 is an RS-232/RS-485 converter designed to provide interface virtually any product to a radio and leased telephone line modems. In normal operation the A2400 is configured to work on the D series protocol, but it may be configured to a special communications mode called the transparent mode. When used in the transparent mode the A2400 module provides an effective radio or leased-line modem interface for equipment that does not use the D series protocol.

In normal operation the A2400 communicates with the host on a polling system; that is, each module responds to its own unique address and must be interrogated by the host. The microprocessor in the A2400 examines any character transmitted to it by the host computer. When the microprocessor detects a valid prompt character ($ or #), it traps the prompt and examines the next characters for a valid address and a valid command. This simple command/response protocol must be strictly observed to avoid communi- cations collisions and data errors.

In the transparent mode the module acts like an open gate for information. Any data presented at the input to the module will be passed on regardless of protocol.

A device that is half duplex and uses a 10-bit NRZ asynchronous data format can be used with the A2400 in the transparent mode. The 10-bit format may consist of 1 start bit, 7 data bits, 1 parity bit, 1 stop bit or 8 data bits without the parity bit.

Transparent Mode Functions

In the transparent mode the A2400 provides the user with the following functions:

1.Ready To Send (RTS) and Clear To Send (CTS) handshaking signals for RS-232 devices to interface to equipment that require those handshak- ing signals such as radio or lease-line modems.

2.Networking capability for RS-232 devices by providing unique channel addressing capability.

3.RS-485/RS-232 conversion for RS-485 devices to interface to equipment with an RS-232 port such as modems or a host computer.

Image 60

Contents User’sGuide Servicing North America For immediate technical or application assistanceServicing Europe Revised 4/17/95 Omega Engineering ONE Omega DriveBOX STAMFORD, CT Phone 1-800-DAS-IEEETable of Contents Chapter Getting Started IntroductionSystem Overview Leased Lines$1RD +99999.99Default Mode Page Block Diagram Chapter Functional DescriptionFunctional Description Pinout RS-485 Termination A2400 OperationCharacter Filter Page Programmable Delay Times Page Command $1RD Response *+99999.99 Chapter CommunicationsDO, OC, CC, RD, REA, RID, RLP, RS, RSP, RSU Communication RS-485 Multidrop System DATA+Page Chapter A2400 Command Set Command StructureData Structure Write ProtectionMiscellaneous Protocol Notes Response StructureCommand Checksum Long Form Responses?1 Syntax Error ?1 BAD Checksum$1WEF A2400 User Commands A2400 Command Set RT3Command Descriptions Command 01CC Response Response *01CC11 Digital Output doCommand $1DO01 Response Command #1DO01 Response *1DO014F Closed Channel CC ExtendedCommand $1DO00 Response Command #1DO00 Response *1DO004E Extended Address EA$1ID Tank Farm #1ID Tank Farm1ID Tank Farm 1CD Command 01OC Response Response *01OCED Open Channel OC ExtendedRead Data RD $1RID Tank Farm#1RID 1RID Tank Farm 11F$1RSU #1RSU$1RSP #1RSPRead Time Delay 1 RT1 Response *1RT1+00100.00DC Read Time Delay 2 RT2Response *+00100.00 Page Page Short Prompt SP Command 01WE Response *01WE27 Error MessagesAddress Error BAD ChecksumCommand Error Parity ErrorSyntax Error Value ErrorChapter Setup Information/SetUp Command Command Syntax$1SUbyte 1byte 2byte 3byte Byte Byte 1 Ascii Printable Characters HEX AsciiParity Baud RateCommand $1RS Response *31070000 Command $1WE Response Command $1SU31020000Command $1RS Response *31020102 Command $1WE Command $1RR Response BitByte 2 Linefeed, Parity and Baud Rate BaudNormal addressing Chapter Delay Time Programming Delay Time Programming Page Command $1T3+00050.00 Set T3 to 50 ms Response Command $1RT1 Response *+00100.00Chapter Power Supply Chapter Troubleshooting Symptom RS-232 Module is not responding to commandsSymptom RS-485 Module is not responding to commands Command 01WE Response Open/Close Channel CommandsChapter Extended Addressing Typical system overview Command 01OC Response Command $1RD Response +00100.00 Typical $2RD +00123.45Command 01CC Response Command 02OC ResponseStructured Addressing Extended Address SyntaxOC and CC Command Formats Implied CC CommandImplied OC Command Command ResponseCommand Response *01OC1D Single Command Module Address Command 01$1RD Response *+00100.00Explicit Open and Close Channel Commands Command 01CC Response 01CC11 ‘11’ is the checksum Command 02OC Response 02OC1E ‘1E’ is the checksumChapter Transparent Mode Transparent Mode FunctionsA2400 interfacing a PLC to a leased-line modem A2400 networking several RS-232 devices to a host computer A2400 interfacing a laboratory instrument with modules Transparent Mode Adding secondary control using A2400 modules Transparent Mode WARRANTY/DISCLAIMER Shop online at omega.com