Resolving TISOFT v7.1 Windows 7 Echo Off and Project Load Errors

Overview of TISOFT v7.1 and the TI505 Platform

TISOFT is the legacy programming and configuration tool for the Texas Instruments TI505 / Siemens 505 family of programmable logic controllers. The TI505 line was originally released by Texas Instruments and migrated to Siemens after the SIMATIC TI acquisition; the platform remained in service for decades in HVAC, water/wastewater, batch process, and discrete machine control applications.

The final DOS-based release, TISOFT v7.1 (and its sibling TISOFT2 Rel. 6.3), is documented in the Siemens user manual 505 TISOFT2 Rel. 6.3 User Manual (TS505-8101-7). These releases are 16-bit DOS applications. They were never recompiled for 32-bit Windows and have no native NTVDM support in modern Windows editions.

Engineers encountering TISOFT in the field today are typically maintaining installed-base systems that predate the migration to SIMATIC Step 5 and Step 7 / TIA Portal. Common pain points on Windows 7 (and later) include:

• The application starts but no prompt is returned (the "echo off" symptom).
• Projects refuse to open with file-open dialog errors or path corruption.
• Online connection to the PLC fails even with correct cable wiring.
• Batch files (TI505.bat) launch but the application aborts before any menu loads.

This reference documents the architectural root cause of each of those failures and provides verified recovery paths.

Why TISOFT v7.1 Fails on Windows 7

TISOFT v7.1 was engineered for the following environment:

• CPU: Intel 8086/8088 or 80286/80386 real mode.
• OS: MS-DOS 3.3 through 6.22, Windows 3.1, Windows 95, Windows 98, Windows ME, and Windows NT 4.0 with NTVDM.
• Memory model: Conventional memory plus upper memory blocks (UMB). The installer relies on a 640 KB conventional-memory ceiling.
• I/O: Direct COM port access via BIOS interrupt 14h. No plug-and-play enumeration.

Windows 7 removed the NTVDM subsystem for 16-bit DOS applications in 64-bit editions, and even the 32-bit edition's NTVDM is restricted to signed, Microsoft-trusted components under User Account Control (UAC). Several underlying dependencies in TISOFT 7.1 are unsigned, so Windows 7 silently blocks them.

Root Cause Analysis: The Echo Off Symptom

The "echo off" behavior is the visible symptom of three distinct failure modes, each requiring a different corrective action.

Each mode has the same surface symptom — a black console window with the title "TI505" but no output — but the corrective action is different. The diagnostic table below is the fastest field-deck triage method.

Prerequisites for Restoring TISOFT v7.1 Operation

Before any of the recovery paths below, confirm the following are in place:

1. Windows 7 edition and bitness. Windows 7 Professional, Enterprise, or Ultimate is required for Windows XP Mode. Starter, Home Basic, and Home Premium do not include the XP Mode download.
2. Architecture match. 32-bit Windows 7 hosts run XP Mode natively. 64-bit Windows 7 hosts require a hardware-assisted virtualization CPU (Intel VT-x or AMD-V) enabled in firmware.
3. RAM and disk. Allocate at least 1 GB of RAM and 15 GB of dynamic disk to the Windows XP virtual machine.
4. Original TISOFT media. Either the v7.1 release disks or the v6.3 release referenced in TS505-8101-7. Disk images (IMG/IMA) can be mounted in the virtual machine.
5. USB-to-serial converter. Any FTDI FT232R, FT230X, or Silicon Labs CP210x-based bridge is acceptable. Industrial-grade converters with surge protection (B&B Electronics USOPTL4, Phoenix Contact PSM-ME-RS232/RS485-P) are preferred for plant-floor noise immunity.
6. TI505 programming cable. A null-modem RS-232 cable wired for the TI505 serial port pinout (DB-25 on the PLC side, DB-9 on the PC side, with TX/RX/GND crossed and RTS/CTS looped back at the PC end).

Installing Windows XP Mode on Windows 7

Windows XP Mode is a free download from Microsoft that delivers a pre-built Windows XP SP3 virtual hard disk and a Virtual PC integration layer. It is the most reliable path for running TISOFT v7.1 because TISOFT sees a true Windows XP environment with full NTVDM support, signed drivers, and direct COM port access.

Step-by-Step Procedure

1. Download WindowsXPMode_en-us.exe and Windows6.1-KB958559-x86-RefreshPkg.msu (the Virtual PC platform update) from the Microsoft Download Center archive. Validate SHA-1 against Microsoft's published checksums.
2. Install the Virtual PC platform update first. Reboot when prompted.
3. Run the Windows XP Mode installer. Specify a clean location on a fixed disk (do not place the VHD on a network share or USB drive — NTFS compression must be off and write caching must be on).
4. Launch Windows Virtual PC from the Start menu. Double-click Windows XP Mode.
5. Accept the license, set the install password, and enable automatic updates. Disable the integration features checkbox (Disable Integration Features). Integration features are not required for TISOFT and can introduce COM port redirection conflicts.
6. Apply Windows XP SP3 plus post-SP3 hotfixes. Confirm ver reports 5.1.2600 Service Pack 3.

The resulting XP Mode VHD is a fully signed 32-bit Windows XP image. NTVDM is enabled by default. TISOFT v7.1 will install and run on this image with no further compatibility configuration.

Mapping USB-to-Serial Converters into the Virtual PC

The PLC serial port is the only path for TISOFT to communicate with a TI505 CPU. Modern PCs and laptops typically lack a built-in DB-9 port, so a USB-to-RS-232 bridge is required. Mapping that bridge through Virtual PC requires two stages: Windows 7 host enumeration, and Windows XP guest passthrough.

Stage 1 — Host Driver Installation

1. Plug the USB-to-serial converter into a USB 2.0 port. Avoid USB 3.0 ports on Windows 7 hosts — the Microsoft USB 3.0 stack has known enumeration glitches that can cause the bridge to disappear after sleep/resume.
2. Install the manufacturer's signed driver (FTDI VCP driver 2.12.x or CP210x VCP 6.7.x). Confirm in Device Manager → Ports (COM & LPT) that the bridge appears as e.g. USB Serial Port (COM3).
3. Set the COM port number below 10 if possible. COM port numbers above 9 require the legacy \DosDevices\COMxx namespace and are not always correctly mapped by Virtual PC.

Stage 2 — Guest Passthrough

1. With the virtual machine running, click Tools → USB in the Virtual PC toolbar. The host's USB devices are listed.
2. Select the USB Serial Converter entry. Capture it to the guest.
3. In the Windows XP guest, open Device Manager. The bridge should now appear as a COM port. Note the COM number assigned by the guest (e.g. COM1).

Serial Port Configuration

TISOFT's default serial configuration for the TI505 NIM (Network Interface Module) is:

Match the same parameters on the converter's advanced properties dialog (Ports → Advanced → COM Port Number, and any baud-rate divisor overrides).

Configuring TISOFT Serial Port Parameters

Once TISOFT v7.1 launches inside the XP Mode VM, configure the offline defaults so the application knows where to find the PLC.

1. Edit the TI505.bat shortcut to call the executable directly without redirecting output:

   @echo off
   cd \TISOFT\BIN
   TI505.EXE /PORT=1 /BAUD=19200 /PARITY=E /BITS=7 /STOP=1

2. Open the Setup → Communication menu. Confirm the COM port matches the one assigned in Device Manager.
3. Set Online Timeout to 10 seconds. Lower values cause false timeouts on busy networks.
4. Save the configuration to TISOFT.CFG in the install root.

Test the connection from the Online → Connect menu. A successful connection returns the PLC model number and firmware revision (for example, TI545-1102 FW 3.41). If the connection still times out, the issue is at the cable layer, not TISOFT.

Alternative Path: Migrating to PLC Workshop for 505

For maintenance teams that have moved past Windows 7, virtualization adds operational overhead: an XP Mode license, a virtual machine lifecycle, and dual-driver maintenance. A native Windows alternative removes all three.

PLC Workshop for 505 (Fast-Soft) is a 32-bit and 64-bit native Windows application that supports the TI505 instruction set, including the legacy SF, SP, SG, SR, and arithmetic functions documented in the TISOFT2 Rel. 6.3 user manual. It supports Windows XP, Vista, Windows 7, Windows 8, Windows 10, and Windows 11, both 32-bit and 64-bit, with no virtualization layer.

Migration Procedure

1. Export the offline program from TISOFT as a .PGM ASCII file using File → Export → ASCII Program.
2. In PLC Workshop for 505, open the PGM file. The import wizard maps TISOFT mnemonics 1:1 to the equivalent PLC Workshop tag set.
3. Recompile the program. PLC Workshop performs the same ladder logic validation as TISOFT, including rung-length checks and I/O reference range validation against the TI505 reference map.
4. Compare the compiled binary against the original TISOFT-compiled binary using Tools → Compare → Program. Differences should be zero on the application code segments.
5. Download and monitor in Online Mode. Use PLC Workshop's live tag view to confirm timing-sensitive I/O.

TISOFT 6.3 Reference: Manual Installation on Legacy Windows

The earlier TISOFT2 Rel. 6.3 release installs identically to v7.1, and its installer is documented in section 1 of the official manual TS505-8101-7. Manual installation steps (still useful when running the installer inside a virtual machine):

1. Create the install directory: mkdir C:\TISOFT.
2. Insert Disk 1. Run INSTALL.EXE.
3. Select Typical Install unless a custom directory is required.
4. When prompted for the parallel port key, choose Skip if no security key is attached. TISOFT will run in unsecured mode.
5. After installation, append the install path to AUTOEXEC.BAT:

SET PATH=%PATH%;C:\TISOFT\BIN
SET TISOFT=C:\TISOFT

6. Reboot into the XP Mode VM and run TI505.BAT from the command prompt.

The same procedure applies to TISOFT v7.1 with the v7.1 install media substituted in step 2.

Verification and Commissioning Checklist

After the recovery path is deployed, run through this checklist before declaring the workstation ready:

Troubleshooting Matrix

FAQ