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McQuay Micro Tech Open Protocol Driver Manual Page 3 of 35
FieldServer Technologies 1991 Tarob Court Milpitas, California 95035 USA Web: www.fieldServer.com
Tel: (408) 262 2299 Fax: (408) 262 2269 Toll Free: (888) 509 1970 email: support@fieldServer.com
1. McQuay Micro Tech Open Protocol Description
This document describes the FieldServer driver used to transfer data between a FieldServer and
MicroTech® controllers. Transfers are done using the controller's Data Terminal Communications
Protocol. In this document the protocol is referred to as the McQuay Micro Tech Open Protocol.
The McQuay Micro Tech Open Protocol driver allows the FieldServer to transfer data to and from devices
over either RS-232 or RS-485 using McQuay Micro Tech Open Protocol. The FieldServer can emulate
either a Server or Client.
When emulating a Client, the driver enables the FieldServer to request ‘Everything’ from the McQuay
device as well as a number of advanced options which allow specific fields to be read or written and
device scaling to be applied.
When emulating a Server, the driver provides an emulation of the byte memory of a device and responds
to read and write requests.
The following important points and limitations should be noted before proceeding with this manual.
1. Arising from a feature of the McQuay Micro Tech Open Protocol is the peculiarity, that when a multi-
byte value is written to a McQuay device, the write is done one byte at a time (one byte of data can
be transferred per poll/response message pair) allowing for the possibility (at least for a short period)
that the multi byte value is only partially correct until all the messages have been completed.
2. The vendor equipment is limited to a maximum of 9600 baud. Given that each message packet can
only transfer one byte of data and that some data of interest is multi-byte, users of this protocol
should expect low data transfer rates.
3. Port expansion is not supported for this driver.
4. A document identified as Ed15050 MicroTech Network Operations contains important information
regarding the connection requirements of 3rd party equipment such as the FieldServer to a Microtech
network. The document also defines a number of limitations for such connections. The following
quotations from this document outline some of this information.