Specifications

Data Exchange
890USE17700 September 2003 117
Data and Status
Objects
Data exchange between the island and the fieldbus master involves three object
types:
data objects, which are operating values that the master either reads from the
input modules or writes to the output modules
status objects, which are module health records sent to the input area of the
process image by all of the I/O modules and read by the master
echo output data objects, which the digital output modules send to the input
process image; these objects are usually a copy of the data objects, but they can
contain useful information if a digital output channel is configured to handle the
result of a reflex action.
A Data Exchange
Example
The example uses the sample island bus assembly, as illustrated in the following
figure. The sample island comprises the STB NIP 2212 NIM, eight Advantys STB
I/O modules, a 24 VDC PDM, and an STB XMP 1100 termination plate:
1 STB NIP 2212 network interface module
2 24 VDC power distribution module
3 STB DDI 3230 24 VDC two-channel digital input module
4 STB DDO 3200 24 VDC two-channel digital output module
5 STB DDI 3420 24 VDC four-channel digital input module
6 STB DDO 3410 24 VDC four-channel digital output module
7 STB DDI 3610 24 VDC six-channel digital input module
8 STB DDO 3600 24 VDC six-channel digital output module
9 STB AVI 1270 +/-10 VDC two-channel analog input module
10 STB AVO 1250 +/-10 VDC two-channel analog output module
11 STB XMP 1100 island bus termination plate