Setting Up LOGO! 0BA6 Teleservice via PSTN and GSM Modems

Overview: LOGO! 0BA6 Teleservice Architecture

The Siemens LOGO! 0BA6 generation (introduced in 2009, predecessor to the current LOGO! 8 / 0BA8 line) exposes a service-oriented remote maintenance workflow called Teleservice. Unlike SMS-based telemetry or one-way GSM alarms, Teleservice provides a transparent RS-232 bridge between a remote LOGO!Soft Comfort engineering station and the on-site LOGO! TD (text display) or LOGO! 0BA6 base module. The transparent bridge permits full program upload, download, online test, online variable monitoring, and password-protected write access over the public switched telephone network (PSTN) or a GSM/3G cellular bearer.

This article documents the verified hardware stack (Siemens LOGO! 0BA6 + INSYS Pocket 56K + 6ED1057-1CA00-0BA0 cable) and extends the workflow to GSM cellular scenarios, including the critical 10-bit / 11-bit serial framing conversion that the on-board LOGO! serial port requires.

Prerequisites

Update LOGO!Soft Comfort to V6.1.x using the Help -> Update Center menu. Without V6.1, the modem configuration dialog cannot be reached and only direct serial LOGO! connections can be edited.

LOGO! 0BA6 Serial Protocol Characteristics

LOGO! 0BA6 communicates with LOGO!Soft Comfort over an asynchronous serial link with the following fixed attributes:

The 11-bit frame is the root constraint behind every GSM Teleservice deployment. GSM cellular bearers, when programmed with their default profile, transmit serial frames with no parity bit (1 start + 8 data + 0 parity + 1 stop = 10 bits). The on-site LOGO! rejects all 10-bit frames as framing errors and the Teleservice session never establishes.

PSTN Teleservice Configuration with INSYS Pocket 56K

Hardware Topology

The verified topology pairs two INSYS Pocket 56K analog modems across a public PSTN line:

• Remote engineering PC ↔ 6ED1057-1AA01-0BA0 (USB) ↔ INSYS Pocket 56K (client side, dials out)
• PSTN line (analog subscriber, DTMF, 56 kbit/s downstream fallback to V.90/V.92)
• On-site INSYS Pocket 56K (auto-answer) ↔ 6ED1057-1CA00-0BA0 LOGO! modem cable ↔ LOGO! 0BA6 base module

On-Site Modem Setup

1. Connect 6ED1057-1CA00-0BA0 between the INSYS Pocket 56K DB-9 and the LOGO! base module service port (RJ-12).
2. Power the modem from the included 12 V wall adapter or a 24 V DC industrial supply (the INSYS accepts 9-30 V DC).
3. Connect the analog PSTN line to the modem's RJ-11 Line jack.
4. Insert a solder bridge or use the configuration utility to set S0 = 2 (auto-answer on second ring) and &D2 (DTR-controlled hang-up).
5. Disable any error-correction / data-compression fallback that breaks the 11-bit frame (set &Q0, \N0, no V.42 bis).

LOGO!Soft Comfort Modem Configuration (Remote PC)

1. Open LOGO!Soft Comfort V6.1+ and choose Tools -> Modem Configuration.
2. Select PC → Modem as the direction.
3. Select the COM port assigned to the local INSYS Pocket 56K.
4. Enter the dial string for the on-site modem, e.g., ATDT,,,0049891234567 (commas provide a 2-second wait each to traverse PBX dial tone delays).
5. Save the configuration as modem_0BA6_PSTN.lsc.

Connecting

1. In LOGO!Soft Comfort, choose Tools -> Connect Modem. The PC modem dials.
2. After the on-site modem answers (second ring), the carrier light must go solid within 6-8 seconds.
3. LOGO!Soft Comfort negotiates the LOGO! protocol handshake; the status bar shows Online Test Active.
4. Use Tools -> Upload / Download / Online Test transparently as if the LOGO! were connected directly to the PC.

GSM Teleservice Configuration

Bearer Selection: CSD vs. GPRS

GSM Teleservice historically rides Circuit Switched Data (CSD, transparent 9.6 kbit/s, billed per minute). GPRS is unsuitable because it is packet-switched and breaks the synchronous RS-232 timing required by LOGO!. Verify that:

• The cellular subscription includes a CSD data number (often an MSISDN different from the voice line).
• The modem module is configured in CSD transparent mode (AT+CBST=71,0,1 for 9600 bps V.110 on Wavecom).
• Network still supports CSD; many operators have sunset CSD in mature markets — verify before commissioning.

Parity / Framing Conversion (Critical Step)

The on-site GSM modem must present Even parity on its RS-232 port regardless of what the air interface carries:

AT+ICF=3       (8 data bits, even parity, 1 stop bit)
AT+IFC=2,2     (RTS/CTS hardware flow control on both directions)
AT+IPR=19200   (force DTE rate to match LOGO! 0BA6 service port)
AT&W           (save profile to NVRAM)

Issuing AT+IPR=19200 with AT&W locks the DTE rate so the LOGO! never sees a rate-mismatch framing error after power cycles.

Auto-Answer for Teleservice

ATS0=2        (auto-answer on second ring, CSD only)
AT+CRC=0       (raw bearer, no cellular result codes)
AT&W

For unattended sites, add AT#ENVG=0 on Wavecom Q24-class modules to disable unsolicited URCs that may otherwise corrupt the LOGO! frame stream during idle periods.

Power and Antenna Considerations

Generator switchboards typically present high electromagnetic transients (load steps, paralleling breaker operations, cranking surges). Apply:

• 24 V DC supply derived from the starter battery with a 2 A DC-DC isolator and TVS diode (e.g., 33 V SMAJ33CA) on the input.
• SMA-mounted antenna external to the switchboard enclosure, fed with RG-174 or LMR-200 through the panel gland.
• Ferrite on the RS-232 cable between modem and 6ED1057-1CA00-0BA0, plus a separate ferrite on the antenna feed (3-5 turns, type 31 material).

Cable Pinout Reference: 6ED1057-1CA00-0BA0

The cable provides null-modem-style crossing on TX/RX and full hardware handshake; do not substitute a generic DB-9-to-RJ-12 because the LOGO! service port pinout does not follow the standard 6P6C Ethernet pinout.

Verification Procedure

1. With both modems powered and the PSTN/GSM bearer idle, verify the on-site modem's CD (Carrier Detect) LED is OFF.
2. From the remote PC, launch Tools -> Connect Modem; confirm dial tone, dialing, and remote answer (CD ON within 8 seconds for PSTN, 12-30 seconds for GSM CSD including network attach).
3. LOGO!Soft Comfort status bar must transition to Connected; if it hangs at Initializing, drop the session and check that the on-site modem's parity is set to Even.
4. Open Online Test; values in I, Q, M, AI, AQ, V must update at approximately 1 Hz.
5. Perform a read-only Upload from LOGO! and diff against the as-built program to prove the bidirectional path.
6. Close the session via Tools -> Disconnect; confirm the on-site modem hangs up within 60 seconds (DTR drop).

Troubleshooting Matrix

Common Pitfalls and Field Notes

• Do not use the same COM port for the LOGO! USB cable and a USB GSM modem without verifying that the OS assigns distinct COM numbers (Windows may enumerate both as COM3 on hot-plug).
• Do not terminate Teleservice sessions by closing the LOGO!Soft Comfort window — always use Disconnect; abrupt closure leaves the on-site modem holding the carrier.
• Do provision a watchdog (LOGO! V-memory bit driven from the LOGO!Soft Comfort "keep-alive" pulse) so the generator controller re-initializes the modem if it hangs.
• Do lock the SIM card PIN in the GSM modem (or disable PIN) so a SIM-swap does not brick the Teleservice path.
• Consider adding an RTC battery-backed real-time clock trigger in the LOGO! program to wake the modem on schedule rather than leaving it always-on; this reduces RF exposure and operator data costs.

Migrating from 0BA6 to LOGO! 8 (0BA8)

If new deployments are planned, the LOGO! 8 generation replaces the 11-bit serial protocol with native Ethernet and a built-in Web server. Teleservice over Ethernet uses LOGO!Soft Comfort V8.0+ with the LOGO! BM's IP address or hostname, no modem required. Existing 0BA6 sites can be retrofitted with an external cellular-to-Ethernet gateway (e.g., a ProSoft RLX-ICM or a Sierra Wireless RV50) to bridge legacy gear to modern SCADA without re-engineering the LOGO! program. The 6ED1057-1CA00-0BA0 cable is specific to the 0BA6/0BA7 service port and is not used with LOGO! 8.

Document References

Refer to the Siemens LOGO! 0BA6 manual (chapter "Communication / Teleservice") and the LOGO!Soft Comfort online help for the V6.1 modem configuration workflow. The Siemens Support entry titled How do you set up a teleservice connection to LOGO! with LOGO!Soft Comfort? (entry ID 37408429) contains the canonical procedure validated against the INSYS Pocket 56K and is the primary reference for new commissioning engineers.