Serial Communications 3104
REC XXXXX 1-2
The hardware can be configured (through jumpers on the Mother Board and on the
optinally COMM board if available) to one of the three standards as listed in the
previous paragraph. However, only the RS485/RS422 standard allows multidrop
communications, RS232C and Current Loop can only be used in point to point mode.
This does not prevent the use of a protocol; it only prevents physically connecting the
Micro-Tech 3000 to more than one device.
CAUTION
The communication protocols have been implemented and tested as
described in this document or in other referenced documents. It is
the intention of Thermo Ramsey to provide all the necessary
information and help the user to connect the instrument to other
compatible devices. However, because most of the protocols are
specific to other manufacturers, Thermo Ramsey declines any
responsibility for any malfunction that may occur when connecting
the instrument to devices of other manufacturers, unless tested and
approved by Thermo Ramsey.
1.2.1 Protocol Rules
The communication protocol allows a remote intelligent device to read and
eventually write information from and to the Micro-Tech 3104. For
convenience, the information is organized in a set of registers as listed in this
document.
During the communication activity, the Micro-Tech 3104 always acts as Slave,
meaning it responds to a request from a Master device on the line, but never
attempts to send messages out.
The following rules apply:
a. The Micro-Tech 3104 responds only if the message is completely
received.
b. The Micro-Tech 3104 reads the message and looks for the address,
which is contained into an address byte in the query package. The
message is then processed only if the address matches the one specified
in the set-up data of the Micro-Tech 3104, otherwise it is ignored.
c. When the system receives a message, the integrity of the message is
checked. An answer-back message is prepared if the message is
formally correct.
d. When a message containing a variable to be written in memory is
received, the system checks the correctness of the message and, if it is
correct, immediately sends the answer-back message. This does not
always mean the data is written in memory. The system first checks the
register number (which must correspond to a valid address of a variable),
then the minimum and maximum limits, and then the password. If data
can be accepted, it is stored in memory and the success flag is set to 0
(no error). If not, it is set to 1. To know if the last variables sent have
been stored, the Master checks (reads) the success flag contained in a
read only register.
The following procedure applies:
- The Host sends data to the Micro-Tech 3104.
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