Crestron ST-COM User Manual
This document was prepared and written by the Technical Documentation department at:
Crestron Electronics, Inc.
15 Volvo Drive
Rockleigh, NJ 07647
1-888-CRESTRON
Crestron ST-COM RS-232/422/485 COM Module
Contents
RS-232/422/485 COM Module: ST-COM 1
Description.................................................................................................................................1
Functional Description ................................................................................................1
Physical Description.................................................................................................... 2
Leading Specifications...............................................................................................................5
Setup .......................................................................................................................................... 7
Identity Code ............................................................................................................... 7
Preparation for Use...................................................................................................... 7
Firmware Upgrade....................................................................................................... 9
Programming with SIMPL Windows ......................................................................................12
Configure a ST-COM Program ................................................................................. 12
ST-COM Symbol ......................................................................................................13
Example Program......................................................................................................14
Problem Solving ...................................................................................................................... 15
Troubleshooting......................................................................................................... 15
Further Inquiries........................................................................................................15
Future Updates ..........................................................................................................16
Future Firmware Upgrades........................................................................................ 16
Return and Warranty Policies..................................................................................................17
Merchandise Returns / Repair Service ......................................................................17
CRESTRON Limited Warranty.................................................................................17
Operations Guide - DOC. 5695A RS-232/422/485 COM Module: ST-COM • i
Crestron ST-COM RS-232/422/485 COM Module
RS-232/422/485 COM Module: ST-COM
Description
Functional Description
There are two Crestron RS-232/422/485 COM module configurations available:
ST-COM and STI-COM. All of the features are identical with the exception of input
power requirements and unit nomenclature. The ST-COM uses a power pack rated
for 120 VAC supply and the STI-COM uses a power pack rated for 220 VAC. Use of
the power packs are optional within a Cresnet system. For purposes of this
Operations Guide, the term ST-COM is used for either configuration, except where
noted.
The ST-COM is a device with two independent bidirectional serial ports that can
support RS-232, RS-485, or asynchronous RS-422-based communication. The unit
enables a system to overcome the distance limitations of serial communication. It can
be used as part of the Cresnet system or SmarTouch STS to add control for
additional serial devices such as video projectors or AV switchers. If part of the
Cresnet system, use of the power pack is optional.
Both ports of the ST-COM may be used to control a wide variety of RS-232,
RS-485, or asynchronous RS-422 controlled equipment. A variety of
communications parameters are supported. Valid parameters are as follows.
• Baud rates may be one of the following possible rates: 300, 1200,
1800, 2400, 3600, 4800, 6100, 7200, 9600, 14400, 19200, 28800,
38400, 57600, and 115200. When specifying the baud rate on a port, do
not use commas.
• Parity may be even, odd, none, or zero stick (parity bit always 0). When
specifying the parity use E, O, N, or Z, respectively.
• Data bits may be 7 or 8.
• Stop bits may be 1 or 2.
• Both XON/XOFF handshaking and RTS/CTS handshaking are
supported. XON/XOFF handshaking may be supported by specifying
XON (for both transmit and receive), XONR (for receive only), or
XONT (for transmit only). XON/XOFF and RTS/CTS handshaking are
Operations Guide - DOC. 5695A RS-232/422/485 COM Module: ST-COM • 1
RS-232/422/485 COM Module Crestron ST-COM
mutually exclusive in the ST-COM. If both are enabled, RTS/CTS is
used. If CTS handshaking is enabled, the CTS line is monitored by the
ST-COM. The CTS line can also be enabled as a digital input to the
control system; the RTS line can be enabled as a digital output.
• Specify RS422 for standard if RS-422 compatible levels must be
supported.
• Break statement is generated for as long as the signal is held high.
• Provides character pacing in units of milliseconds for all of the data
specified. The range of the pacing is from 1 to 31 milliseconds. Pacing
greater than 31 milliseconds defaults to the maximum (31 ms).
• Supports RS-485. However, additional drivers are required and specific
protocol must be followed. The unit remains in receive mode until
transmission is enabled with one character switching. Consult
Crestron’s award winning customer service team in your area.
Physical Description
The ST-COM is housed in a black enclosure with silk-screened labels on the front
and rear panels. On the front of the unit there are 10 LEDs for indicating the unit’s
current status. All connections are made on the back of the unit. Refer to the physical
views shown below. There are four rubber feet on the base of the unit for stability
and to prevent slippage.
ST-COM Physical Views
6.322 in
(16.058 cm)
1.500 in
(3.810 cm)
6.134 in
(15.580 cm)
6.940 in
(17.628 cm)
7.066 in
(17.948 cm)
1.700 in
(4.318 cm)
2 • RS-232/422/485 COM Module: ST-COM Operations Guide - DOC. 5695A
Crestron ST-COM RS-232/422/485 COM Module
ST-COM Ports
A number of ports are provided on the back of the ST-COM. Each has a silkscreened label. Refer to illustration and descriptions below.
ST-COM Ports
12 VDC .5A
This direct current (DC) power socket connector is used to supply power via the
external power pack, when attached. If the power pack is used while 24 VDC is
present on the NET connector, the power pack supplies power to the unit (no current
is drawn from the network).
Crestron recommends specific power packs for its devices. The acceptable power
pack for the ST-COM is Crestron part number PW-1205 (PWI-1210 for the
international version, STI-COM). If a power pack other than this Crestron model is
obtained, verify that it meets the required specifications and polarity as shown
below.
Power Pack Specifications
CRESTRON POWER PACK INPUT SPECS OUTPUT SPECS
PW-1205 120V~60Hz 12VDC .5 A
PWI-1210 230V~50Hz 12VDC 1A
Power Pack Output Connector Polarity
NET
These two 6-pin, 6-position RJ11 modular jacks are used to connect the ST-COM
module to either the SmarTouch STS or Cresnet remote control system. When the
module is part of the Cresnet system, power is provided via the NET connection; the
power pack need not be attached. Two NET ports are available so that network units
can be daisy-chained together. Review the latest revision of the Network Modular
Cable Requirements (Doc. 5682).
NOTE: Most 4-conductor phone cables are wired in a crisscross fashion and are not
compatible with Crestron equipment.
NOTE: The ST-CP does not supply network power. Therefore, use the power pack
to supply power to the ST-COM.
If a power pack is attached when the module is part of the Cresnet system, power is
drawn from the power pack. The module does not load the network power, but the
network remains chained for additional network devices that are connected.
Operations Guide - DOC. 5695A RS-232/422/485 COM Module: ST-COM • 3
RS-232/422/485 COM Module Crestron ST-COM
(
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COM A/B
These two nine-pin connectors (DB9) connect to serial equipment. These
bidirectional serial ports are used for RS-232, RS-422, or RS-485 communication.
NOTE: The pinout of each nine-pin port is non-standard (refer to table after this
note); it contains RS-422 pins in addition to RS-232. This may result in a conflict
with some equipment and therefore do not use all nine pins. Only the required pins
for each communication type should be connected.
NOTE: To support RS-485, tie pin 1 (RXD-) to pin 9 (TXD-) and pin 4 (TXD+) to
pin 6 (RXD+) in the cable, as shown below.
ST-COM Pinout (COM A / B)
PIN DIRECTION DESCRIPTION
1* To ST-COM
2To ST-COM
3 From ST-COM
4 From ST-COM
5
6To ST-COM
7 From ST-COM
8To ST-COM
9 From ST-COM
* RS-422 transmit and receive are balanced signals requiring two lines plus a ground in each direction.
RXD+ and TXD+ should idle high (going low at start of data transmission). RXD- and TXD- should idle
low (going high at start of data transmission). If necessary, RXD+/RXD- and TXD+/TXD- may be
swapped to maintain correct signal levels.
(RXD-) RS-422 Receive Data (Idles low)
RXD) RS-232 Received Data
TXD) RS-232 Transmitted Data
TXD+) RS-422 Transmit Data (Idles high
RS-232 and RS-422 Si
RXD+) RS-422 Receive Data (Idles high
RTS) RS-232 Request to Send
CTS) RS-232 Clear to Send
TXD-) RS-422 Transmit Data (Idles low
nal Common
4 • RS-232/422/485 COM Module: ST-COM Operations Guide - DOC. 5695A
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