Omega manual A2400 User Commands

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Command Set 4-5

Example: Append a checksum to the command $1WE

Characters:

$

1

W

E

ASCII hex values:

24

31

57

45

Sum (hex addition)

24 +

31 +

57 +

45 = F1

The checksum is F1 (hex). Append the characters F and 1 to the end of the message: $1WEF1

Example: Verify the checksum of a module response *1WEF7

The checksum is the two characters preceding the CR: F7

Add the remaining character values:

*

1

W

E

 

 

2A +

31+

57+

45

=

F7

The two lowest-order hex digits of the sum are F7 which agrees with the transmitted checksum.

Note that the transmitted checksum is the character string equivalent to the calculated hex integer. The variables must be converted to like types in the host software to determine equivalency.

If checksums do not agree, a communications error has occurred.

If a module is setup to provide linefeeds, the linefeed characters are not included in the checksum calculation.

Parity bits are never included in the checksum calculation.

A2400 User Commands

Table 4.1 shows all the A2400 commands. For each case, a typical command and response is shown. Note that some commands only respond with an * as an acknowledgment. Table 4.1 also separates write protected commands from commands that are not write protected.

For clarity, Table 4.1 separates A2400 Extended Address mode commands from other commands. Note that the Extended Address commands use a different prompt and a two character address.

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Contents User’sGuide Servicing Europe Servicing North AmericaFor immediate technical or application assistance BOX Revised 4/17/95Omega Engineering ONE Omega Drive 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 Character Filter RS-485 TerminationA2400 Operation 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 StructureMiscellaneous Protocol Notes Data StructureWrite Protection Response StructureCommand Checksum Long Form Responses$1WEF ?1 Syntax Error?1 BAD Checksum A2400 User Commands A2400 Command Set RT3Command $1DO01 Response Command #1DO01 Response *1DO014F Command DescriptionsCommand 01CC Response Response *01CC11 Digital Output do Closed Channel CC ExtendedCommand $1DO00 Response Command #1DO00 Response *1DO004E Extended Address EA1ID Tank Farm 1CD $1ID Tank Farm#1ID Tank Farm Read Data RD Command 01OC Response Response *01OCEDOpen Channel OC Extended #1RID $1RIDTank Farm 1RID Tank Farm 11F$1RSP $1RSU#1RSU #1RSPResponse *+00100.00 Read Time Delay 1 RT1Response *1RT1+00100.00DC Read Time Delay 2 RT2 Page Page Short Prompt SP Address Error Command 01WE Response *01WE27Error Messages BAD ChecksumSyntax Error Command ErrorParity Error Value Error$1SUbyte 1byte 2byte 3byte Chapter Setup Information/SetUp CommandCommand Syntax Byte Byte 1 Ascii Printable Characters HEX AsciiParity Baud RateCommand $1RS Response *31020102 Command $1WE Command $1RS Response *31070000Command $1WE Response Command $1SU31020000 Byte 2 Linefeed, Parity and Baud Rate Command $1RR ResponseBit 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 Symptom RS-485 Module is not responding to commands Chapter TroubleshootingSymptom RS-232 Module is not responding to commands Chapter Extended Addressing Command 01WE ResponseOpen/Close Channel Commands Typical system overview Command 01CC Response Command 01OC ResponseCommand $1RD Response +00100.00 Typical $2RD +00123.45 Command 02OC ResponseStructured Addressing Extended Address SyntaxImplied OC Command OC and CC Command FormatsImplied CC Command Command ResponseExplicit Open and Close Channel Commands Command Response *01OC1D Single Command Module AddressCommand 01$1RD Response *+00100.00 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