6. Configuring the Gateway
If the value of a field from the response of a Modbus slave is different from that configured via AbcConf, the response will be rejected by the gateway. It will then proceed to a
Field in the | Size in the | Description | |
frame | frame | ||
| |||
Slave Address | 1 byte | Identical to that of the query’s “Slave Address” field. | |
Function | 1 byte | Identical to that of the query’s “Function” field. | |
Register | 2 bytes | Identical to that of the query’s “Register” field, since the Modbus response of | |
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| any “Preset Single Register” command is an echo to the corresponding query. | |
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| Here you should also enter the address of the memory object to which the | |
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| command relates. | |
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| E.g.: Enter the value 400, converted to 16#0190 by AbcConf. | |
Preset Data | 2 bytes | Data Location: Address, in the gateway’s input data memory (16#0002 to | |
| or more for a | 16#00F3), of the item of data received in the “Preset Data” field for the | |
| block of data | response’s frame. | |
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| N.B. As far as possible, ensure that the data is located at even addresses in | |
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| order to align the Modbus data (in | |
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| ||
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| E.g.: The value sent back as an echo to the command must be placed in the | |
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| gateway’s input data memory area. We shall use the first two free bytes following | |
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| the input data of the default configuration, i.e. addresses | |
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| Data length: Length of the block of input data received in the “Preset Data” | |
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| field of the response frame. It is expressed in number of bytes. | |
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| E.g.: The value of the “Data length” field must be set to 2. | |
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| Byte swap: Identical to that of the query’s “Byte swap” field. | |
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| E.g.: We will also be using the “No swapping” value, for the same reasons as | |
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| with the query. | |
Checksum | 2 bytes | Error check type: Identical to that of the query’s “Error check type” field. | |
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| Error check start byte: Identical to that of the query’s “Error check start bype” field. | |
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| However, these two fields cannot be changed by the user and their values are | |
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| greyed out to reflect this. AbcConf updates the values of these fields | |
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| automatically using those of the query’s “Error check type” and “Error check | |
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| start byte” fields. |
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