CN8240 & CN8260 Series Communications & Options
Digital
Communications Option
The Read Request:
The Read Request is used to query parameter values and it has the following message format: [START CHAR][ID][ZONE][TYPE][PARAM][CHKSUM][END CHAR]
Field Description: TYPE Must contain the uppercase letter ‘R’.
Request Message | Description |
$Ø1Ø1RØ5C1<CR> | Queries the value of the Process Variable |
| of Controller #1. |
$Ø1Ø1RØ9C5<CR> | Queries the value of the EEPROM |
| Setpoint 1 of Controller #1 |
$Ø2Ø1RØ9C6<CR> | Queries the value of the EEPROM |
| Setpoint 1 of Controller #2. |
| END CHAR |
| CHKSUM |
| PARAM |
| TYPE |
| ZONE |
| ID |
| START CHAR |
|
|
Request Messages are sent from the host to the slaves. Each request will have an ID identifying the intended recipient of the request. If the ID is ‘00’ (zero), then the request is a broadcast message.
All slaves will perform the action requested in the broadcast request. However, a response message will not be returned. Therefore, it only makes sense to send Write or Auxiliary Command Requests as broadcast requests.
There are three types of Request Messages: Read, Write, and Auxiliary Commands.
*Examples of the responses to these requests are given in later sections on Response Messages.
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