1734-232ASC — POINT I/O ASCII Serial Communication Module, RS-232

The 1734-232ASC is an RS-232 ASCII serial communication module for the 1734 POINT I/O system. It adds a serial port to a POINT I/O node, allowing the controller to send and receive ASCII-formatted data with devices that don't speak EtherNet/IP or any fieldbus — barcode readers, weight scales, label printers, vision system terminals, and legacy instrument interfaces being the most common examples.

ASCII serial is the lowest common denominator of industrial device communication. Almost any device with a serial port can exchange data in ASCII text format, making the 1734-232ASC a practical bridge when integrating equipment from different eras and manufacturers into a unified control system. The module handles the physical RS-232 layer and the character buffering; the controller program uses the Serial Port Read (SER) and write instructions to send and receive strings.

Specifications

Parameter	Value
Part Number	1734-232ASC
Platform	POINT I/O (1734)
Interface Standard	RS-232C (EIA-232)
Communication Mode	ASCII (full duplex)
Baud Rates	300, 600, 1200, 2400, 4800, 9600, 19200, 38400 bps
Data Bits	7 or 8
Parity	None, Even, Odd
Stop Bits	1 or 2
Connector	DB-9 female (DCE pinout)
Max Cable Length	15 m (RS-232 standard limit)
Receive Buffer	256 bytes
Transmit Buffer	256 bytes
Backplane Current (5V)	75 mA
Operating Temperature	−20°C to 55°C
Standards	UL 508, CE

ASCII Serial in a POINT I/O Node — How It Fits

POINT I/O is a distributed I/O architecture. A node consists of an adapter module (handling the network connection back to the controller) and up to eight I/O modules handling field signals. The 1734-232ASC occupies one of those eight slots and appears to the controller as a communication module in the local I/O tree.

This architecture means you can place the serial interface physically close to the device it communicates with — the barcode reader at the end of a conveyor, the scale at a checkweighing station, the printer at a labelling position — rather than running a long RS-232 cable back to the main panel. The 15 m RS-232 cable length limit from device to module is measured locally; the POINT I/O network handles the connection back to the controller over whatever fieldbus the adapter uses.

Common Integration Scenarios

Barcode and QR Code Readers

Fixed-mount industrial readers at conveyor scan stations are among the most common uses. The reader sends a code string on trigger; the 1734-232ASC buffers it; the controller reads the string, parses the product or lot code, and routes the product accordingly. Response time from scan to decision is typically under 100 ms in a well-structured program.

Checkweighing Scales

Many industrial scales output weight data as ASCII strings at configurable intervals or on command. The controller polls the scale, receives the weight string, parses the numeric value, and compares it to the acceptable range — accept, reject, or re-weigh. The 1734-232ASC sits between the scale's RS-232 port and the POINT I/O node at the weigh station.

Label and Ticket Printers

Industrial label printers typically accept print commands as ASCII strings (or printer-specific markup languages transmitted as ASCII). The controller builds the label content string — date, lot code, weight, SKU — and transmits it via the 1734-232ASC when a print trigger fires. Print confirmation (if the printer supports it) returns over the same connection.

Legacy Instrument Interfaces

Older instruments — temperature controllers, process analyzers, vision systems — often have RS-232 ports as their only digital interface. Integrating them into a modern EtherNet/IP-based control architecture without replacing the instrument is exactly where the 1734-232ASC earns its place.

FAQ

Q: Does this module support RS-485 or RS-422 in addition to RS-232?

No. The 1734-232ASC is RS-232 only. For RS-485 or RS-422 serial communication, the 1734-485ASC module is the appropriate choice within the POINT I/O family.

Q: How is the module configured — software or hardware switches?

All port parameters (baud rate, data bits, parity, stop bits, flow control) are configured in software through the POINT I/O adapter's configuration tool in Studio 5000 or RSLogix 5000. There are no DIP switches or physical configuration elements on the module itself.

Q: What happens to buffered data if the controller goes into fault?

The receive buffer holds up to 256 bytes. If the controller stops reading the buffer during a fault condition and the connected device continues transmitting, the buffer fills and new incoming characters are lost. The module does not have overflow error reporting to the field device — it simply stops accepting characters when the buffer is full.

Q: Can the module communicate with two devices simultaneously?

No. The 1734-232ASC has a single RS-232 port and communicates with one device at a time. For two serial devices at the same POINT I/O node, two 1734-232ASC modules are needed, each occupying one slot.

Q: Is a null modem cable needed to connect to a barcode reader or scale?

It depends on the connected device's pinout. The 1734-232ASC is configured as a DCE device. Most barcode readers and scales are also DCE — connecting two DCE devices requires a null modem cable or adapter to cross the TX/RX and handshaking lines. Check the connected device's datasheet for its RS-232 role (DTE or DCE) before ordering cables.

1734-232ASC New Point I/O ASCII Interface Module 1734232ASC