Delta OHM HD45 Series Manual page 44

Relays state reading (function 01h)
Function code 01h allows to read the relays activation state of the instrument.
The relays state can only be read, there are no commands available for relay state
modification.
The register address for the first relay state and the number of consecutive relays to
be read are indicated in the request data field.
Since registers are numbered starting from 1 in the protocol, and data are addressed
starting from 0, a register address is equal to the register number decremented by 1.
The instrument replies with a byte, whose least significant bit (LSB) indicates the
state of the first addressed relay, while the subsequent bits indicate the state of the
other requested relays. The bits value is 1 if relay is active and 0 if relay is inactive.
The bits following the last requested relay are set to 0 to complete the byte.
Consequently, the Function and Data fields of command and response will have the
following format:
Command
Value
Function: 01h
Data: 0000h to FFFFh
0001h to 007Dh
Response
Value
Function: 01h
Data: 01h
The following table lists the available relays with their register number:
Tab. 8.B: Relays state registers
Register
number
Relay in HD45 models, whatever is the associated parameter
0004
CO relay in HD46 models
2
0005 Temperature relay in HD46 models
0006 Humidity relay in HD46 models
The state reading of the unavailable relays in that particular model is not allowed.
If the request involves the reading of at least one parameter which is not included in
table 8.B, the instrument will answer with the following error message:
Response
Value
Function: 81h
Data: 02h
Length Description
1 byte Relay state reading command
2 bytes First relay address
2 bytes Number of relays to be read (N)
Length Description
1 byte Relay state reading command
1 byte Number of bytes with relay state
1 byte Relay state
Relay
Length Description
1 byte Error in relay state reading
Operation involved a non-existent
1 byte
parameter (Tab. 8.F at page 59)
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From
Notes
Ver.
FW
1.08
1.08
1.08