Communication
C3I10T10
192-120100 N16 C3I10T10 - December 2010
RS232: O [$] Index , [$] Subindex = [$] Value [ ; Value2 ; Value3 ; ...]
RS485: Address O [$] Index , [$] Subindex = [$] Value [ ; Value2 ; Value3 ; ...]
The optional ā$ā preceding Index, Subindex and value stands for āHex-inputā which
means that Index, Subindex and the value to be transferred can also be entered in
hex (e.g. O $0192.2=$C8).
5.2.3. Binary record
The binary record with block securing is based on 5 different telegrams:
ļµ 2 request telegrams which the control sends to Compax3 and
ļµ 3 response telegrams which Compax3 returns to the control.
Telegram layout
Basic structure:
SZ A L D0 D1 ... Dn Crc(Hi) Crc(Lo)
The start code defines the frame type and is composed as follows:
RdObj read object 1 0 1 0 x 1 x x
WrObj write object 1 1 0 0 x 1 x x
Rsp response 0 0 0 0 0 1 0 1
Ack positive command acknowledgement 0 0 0 0 0 1 1 0
Nak Negative command acknowledgement 0 0 0 0 0 1 1 1
Bits 7, 6, 5 and 4 of the start code form the telegram identification; Bit 2 is always
ā1ā.
Bits 3, 1 and 0 have different meanings for the request and response telegrams.
The address is only necessary for RS484.
ļµ the address bit (Bit 0 = 1 ) shows if the start code is followed by an address
(only for RS485; for RS232 Bit 0 = 0)
-> Compax3
ļµ the gateway bit (Bit 1 = 1) shows if the message is to be passed on.
(Please set Bit 1 = 0, as this function is not yet available)
ļµ the PLC bit (Bit 3 = 1 ) allows access to objects in the PLC/Pop format
U16, U32: for integer formats (see bus formats: Ix, Ux, V2)
IEEE 32Bit Floating Point: for non integer formats (bus formats: E2_6, C4_3, Y2,
Y4; without scaling)
With Bit 3 = 0 the objects are transmitted in the DSP format.
DSP formats:
24 Bit = 3 Bytes: Integer INT24 or Fractional FRACT24
48 Bit = 6 Bytes: Real REAL48 (3 Byte Int, 3 Byte Fract) / Double Integer DINT48
/ Double Fractional DFRACT48
ļµ Bits 0 and 1 are used to identify the response
Compax3 ->
ļµ Bit 3 is always 0
The maximum number of data bytes in the request telegram is 256, in the response
telegram 253.
The block securing (CRC16) is made via the CCITT table algorithm for all
characters.
After receiving the start code, the timeout monitoring is activated in order to avoid
that Compax3 waits in vain for further codes (e.g. connection interrupted) The