Micromod Micro-DCI: 53IT5100A Indicator/Totalizer - Manual (Page 67)

APPENDIX B: COMMUNICATIONS
B.1 STANDARD COMMUNICATIONS
Two digital communication channels are provided with this instrument: 1) There is a configuration
port that is an RS-232 serial interface. It is accessed via a 5 pin mini-DIN connector located under
the pull-down door on the front panel (see Figure 1-2). It is used to configure instrument parame-
ters for selected operational characteristics. The parameters are configured with the Hand Held
Configurer (HHC) as described in Section 3, or with a customer supplied PC executing the appropri-
ate software. 2) There is also an RS-422/485 serial interface used to connect the instrument to a
Datalink multi-drop network. Interface connection to the Datalink network is via the rear terminal
board (TB1) of the instrument, pins 19 through 22, as shown in Section 2.
Information in this section applies to both the configuration port and the Datalink interface, with the
following exceptions:
1. The configuration port data rate is 9600 baud, with 8 data bits, and no parity.
2. The configuration port powers up in standard mode suitable for use with the HHC, but
can be switched to binary mode by sending the following four character sequence:
Sent 03H 1BH 0EH 15H
Echoed 1BH 20H 0EH 20H 15H
Note: Numbers used in this section that are expressed in hexadecimal notation
(base 16) are identified with an H after the number.
After echoing the 15H character, the instrument switches to binary mode and is able to
process binary communications messages from that time on. (Characters sent after the
15H and before the 15H echo are ignored.)
3. Once the configuration port switches to binary mode, it remains in that mode as long as
the connection is maintained. The connection is maintained by sending a character at
least once every 30 seconds. If 30 seconds elapses without a character being received
by the instrument through the configuration port, the port returns to standard mode.
4. When in binary mode, the instrument responds to all messages regardless of the ad-
dress to which they are directed.
The Datalink interface requires four conductors: a transmit pair and a receive pair. The voltage lev-
els of each conductor pair conform to the EIA RS-422/485 standard. In accordance with this stand-
ard, the overall Datalink network distance is limited to 4000 feet when #24 AWG twisted pair wire is
used to interconnect the nodes. Adapters are available to convert RS-422/485 to RS-232 or 20 mA
current loops.
In a Datalink network, the instruments communicate as Responders to host or SUPERVISOR-PC
queries. The host or PC functions as the Interrogator and acts as the central control point for the
Datalink network. A maximum of 32 addressable instruments can be connected to a Datalink net-
work. Using the SUPERVISOR-PC in a Datalink network system allows a variety of services to be
implemented as described in the SUPERVISOR-PC Instruction Bulletin, IB 53SU5000.
Appendix B. Communications
B-1