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Instruction Manual IMBus
5. Measuring value format of IMB-pb modules
5.1. Initialisation :
After power-on the IMB-pb module waits for its initialisation by Profibus Master, this means the
Profibus Master must assign the address range to IMB-pb module.
Over the assigned data block size ( = address range ) the IMB-pb module knows the number of bytes
to write on Profibus and calculates from this value how many IMBus measuring inputs shall be col-
lected and provided on the Profibus.
One measuring value consists of 4 bytes, this means when the assigned data block has a size of 4
bytes then the IMB-pb reads only address 1 from IMBus, on an assigned data block size of 32 bytes
the addresses 1…8 are read and provided on Profibus.
( If some addresses are physically not available, then the particular measuring value block is marked
with a flag. )
The maximum assigned data block size can be 244 Byte, this means at maximum 61 measuring in-
puts can be read by IMB-pb module. If more than 61 measuring inputs are needed, then further ad-
dresses can be provided by a second IMB-pb module with another Profibus address.
Example :
The Profibus Master has assigned 19 Bytes data block size to IMB-pb module.
Î The IMB-pb module reads continuously from the IMBus Addresses 1..4 the measuring values
( even if more measuring inputs are available in IMBus ) and sends the 19 bytes data block to
the Profibus Master :
5.2. Measuring data block :
One measuring value data block consists of 4 bytes :
Byte 1 ( = state information )
Bit 7 : 0 = Error ( see bit 6..3 )
1 = Measuring value in Bytes 2..4 is valid
Bit 6 .. 3 : Error code : ( only valid on bit 7 = 0 )
0 = Measuring value could not be read ( i.e. gauge is not connected to
IMBus interface module )
>0 = see manual of IMBus module
Bit 2 .. 0 : Number of digits behind decimal point of value ( 0=1, 1=0.1, 2=0.01, … )
Byte 2..4 ( = measuring value )
24 Bit integer value in 2er complement beginning with high byte
The measuring value is only valid if Byte 1 / Bit 7 = 1.
The decimal point position is defined by Byte 1 / Bit 2..0.
!!! Note : On successful connection of IMB-pb to Profibus, the Bus-Error LED of IMB-pb is switched off.
5. Configuration of IMBus measuring and interface modules
5.1 IMB-im1/2/4/8
1. Short description :
- The IMB-im1/2/4/8 modules allow the connection of inductive probes.
- On default the modules are configured for Tesa halfbridge probes, but the modules can also be deliv-
ered for each other probe type.
Value Adr. 1 (4 Byte) Value Adr. 2 (4 Byte) Value Adr. 3 (4 Byte) Value Adr. 4 (4 Byte) 3 Byte not used (=00h)
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