Isdu Response Payload - Emerson RSTi-OM User Manual

RSTi-OM User Manual
GFK-3212A
12.5

ISDU Response Payload

The ISDU response payload is a JSON object with the fields described below:
Name
op
index
subindex
status
Fields specific to read response (one or more of raw, str, uint may be present:
raw
uint
str
len
If no format is specified in the read request, then the read response will contain data in all three formats when
len ≤ 4. If len > 4, only raw and str formats will be returned. If the read operation fails, no len value or data
values will be returned.
In a read response, the str value will have any trailing NULL bytes removed. The len field will always indicate
the total number of bytes read (including any trailing NULL bytes for string values)
Below is an example of a write-string request/response followed by a read-string request/response and a
read-raw request/response where the topic base path is IOLM:
IOLM/port/1/isdu/request/66b127b7-f39d-40e7-b786- 1cffc8d344a0
{
"op": "write", "index": 24,
"str": "hi there"
}
IOLM/port/1/isdu/response/66b127b7-f39d-40e7-b786- 1cffc8d344a0
{
"op": "write", "index": 24,
"status": "OK"
}
IOLM/port/1/isdu/request/2ee5141e-335b-4e33-bf4e- dedf01a0ff7b
{
"op": "read", "index": 24,
"format": "str"
}
IOLM/port/1/isdu/response/2ee5141e-335b-4e33-bf4e- dedf01a0ff7b
{
MQTT Interface
Type Description
string "op" value from request
integer "index" value from request
integer "subindex" value from request (if present and non-zero)
string "OK" if the request was successful, otherwise an error message.
array An array of integer byte values (decimal)
integer Unsigned integer value
string UTF-8 string data
integer Number of bytes read
Section 12
Jun 2021
123