Despatch Protocol Plus Modbus Communications - Manual (Page 27)

Chromalox Instruments and Controls
A-51643 Rev. 6 10/06/03 21
15 Return Slave No Response Count Number of messages addressed to the
slave for which no response was
returned.
18 Return Bus Character Overrun Count Number of overrun and framing errors.
Table 10 Protocol TM Plus Exception Code Set
Exception Code Description Comments
01 Illegal Function The function code received is not valid or
is not supported.
02 Illegal Data Address The data address received is invalid or is
not accessible due to security setting.
03 Illegal Data Value The data value received is invalid.
5.2 Register and I/O Function Set Description for Protocol
TM
Plus
5.2.1 [01] Read Outputs
Class 1 command. Reads the On/Off status of discrete outputs in the slave. Broadcast is not supported.
Query
The query message specifies the starting output and quantity of outputs to be read. Outputs are addressed
starting at 0.
Example: Query to read outputs 20 . . . 56 from slave address 17.
Field Name Data
Slave address $11
Function $01
Starting address hi $00
Starting address lo $13
Number of outputs hi $00
Number of outputs lo $25
CRC $----