INFICON MDC-360 Thin Film Deposition Controller - Manual (Page 131)

MDC-360 DEPOSITION CONTROLLER
11-3 COMPUTER INTERFACE
The checksum is the compliment of the one byte sum of all bytes from, and
including, the instruction code to the end of the message. If the one byte sum of
all thes
ee data types stored in the MDC-360: one byte, two byte, and three
rmat with the
er ASCII characters,
ultiple byte data types
are dec decimal
Dec
l point position. The decimal point positions for
nd are given in tables along with the parameters’
1 EC S
Following the receipt of each message, the controll
tatus’ message, indicating how the message was received, with the
at:
Inst=253
Length=2
des:
e bytes is added to the checksum, the result should equal 255.
If the sum of all bytes occupies more than one byte, a single byte checksum
can be generated using the expression: checksum=!(Sum MOD 256), i.e. the
checksum is the complement of the remainder byte which results from
dividing the sum of all bytes by 256.
11.6 DATA TYPES
There are thr
byte parameters. All data types are stored as integers in binary fo
most significant byte first. The one byte data types are eith
numeric values (0-255), or 8 bit registers. Some of the m
imal values stored as integers. To convert these values to their
equivalent, use the following equation:
imal Value = (Integer Value)/(10*DP)
where DP is the value’s decima
all the parameters are constant a
range.
1.7 MESSAGE R EIVED STATU
er will send a one-byte
‘received s
following form
Header
Address
Instruction Code
Receive code
Checksum
A value of 253 for the instruction byte indicates that this is a received status
message. The Instruction Code byte indicates the instruction code of the message
that was received. The following table shows a list of possible receive co
Receive Code Description
0 M sage received O.K es .
1 In lid checksum. va
2 In lid instruction cod va e.
3 Invalid message length.
4 Parameter(s) out of range.