FUTEK IPM500 (D500) Digital Display - Manual (Page 3)

2. INTRODUCTION, CUSTOM ASCII SERIAL PROTOCOL
This manual applies to our programmable digital panel meters, counters and timers with Series 2
firmware. Before applying this manual to your device, verify that the label states "Series 2."
The Custom ASCII Protocol, which is the subject of this manual, is a simple serial commu-
nications protocol which is optimized for use with Series 2 programmable digital panel meters,
counters and timers. It is compatible with RS232 and RS485 signals. It supports point-to-point
and multipoint (or multidrop) communications, with addressing of up to 31 devices on the same
RS485 serial data line.
Digital panel meters, counters and timers require a plug-in option board for serial communi-
cations. This can be an RS232 board, RS485 board, or RS585 Modbus board. The RS485 and
RS485 Modbus boards are electrically equivalent, but the RS485 board uses RJ11 connectors,
while the RS485 Modbus board uses RJ45 connectors. The two RJ11 or RJ45 connectors are
wired in parallel to allow daisy chaining with no need for a hub. One of the jacks is equipped with
two indicator LEDs.
The Modbus Protocol is a software-selectable alternative to the Custom ASCII Protocol and can
be used with RS232 or RS485 signal levels. It is an industry standard which allows devices by
different manufacturers to be digitally addressed on the same RS485 serial data line. However, it
is substantially more complex than the Custom ASCII Protocol. For additional information, please
refer to the separate Modbus Protocol Communications Manual.
3. JUMPER SETTINGS & FIELD WIRING FOR SERIAL COMMUNICATIONS
3.1 SAFETY WARNINGS
Digital panel meters, counters, timers and transmitters may be powered with AC (mains) from
95-240V ac ±10% or 95-300V dc with the high voltage power supply option, or 10-34V ac ±10%
or 10-48 Vdc with the low voltage power supply option. To avoid the possibility of electrical shock
or damaging short circuits, always unplug the device before opening the case. Please refer to the
respective device manuals for full safety information and instruction on how to open the case.
Signal wiring changes external to the case can be made safely while the units are under power.
3.2 CONNECTION OF METERS, COUNTERS & TIMERS TO COMPUTER
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